The world of paleoanthropology, the study of ancient humans and their relatives, is poised for a transformative decade. Artificial Intelligence (AI) is set to revolutionize this field, providing researchers with unprecedented tools to uncover the secrets of our ancestors. In the next ten years, AI will not only accelerate discoveries but also refine our understanding of human evolution in ways previously unimaginable. This blog post explores how AI will impact paleoanthropology, from data analysis and fossil reconstruction to educational outreach and ethical considerations.

## Introduction: The Intersection of AI and Paleoanthropology

Paleoanthropology has traditionally relied on meticulous fieldwork and manual analysis of fossils and artifacts. However, the integration of AI promises to enhance these methods, enabling more efficient data processing and offering new insights into our evolutionary past. As AI technology continues to advance, its applications in paleoanthropology are expanding, transforming how researchers approach the study of ancient humans.

### The Promise of AI in Data Analysis

One of the most significant impacts of AI on paleoanthropology will be in data analysis. AI algorithms can process vast amounts of data far more quickly and accurately than human researchers. This capability is particularly useful in paleoanthropology, where data from fossil records, genetic studies, and archaeological findings can be overwhelming.

#### 1. Automated Fossil Identification

AI-powered tools can automate the identification and classification of fossils. Using machine learning algorithms, these tools can analyze the shape, size, and other characteristics of fossil fragments to determine their species and age. This automation can significantly reduce the time and effort required for fossil analysis, allowing researchers to focus on interpretation and hypothesis testing.

#### 2. Predictive Modeling

AI can also be used to create predictive models of human evolution. By analyzing patterns in fossil records and genetic data, AI algorithms can generate hypotheses about how different hominin species evolved and migrated over time. These models can help researchers identify gaps in the fossil record and guide future excavations.

### Enhanced Imaging and Reconstruction Techniques

The use of AI in imaging and reconstruction techniques is another area where significant advancements are expected. AI can enhance the resolution of imaging technologies, such as CT scans and MRI, and assist in the reconstruction of incomplete fossils.

#### 1. Improved Imaging Resolution

AI algorithms can enhance the resolution of imaging technologies, allowing researchers to examine fossils in greater detail. This improvement can reveal previously unnoticed features and provide new insights into the morphology and biomechanics of ancient hominins.

#### 2. Digital Reconstruction

AI can assist in the digital reconstruction of incomplete fossils. Machine learning algorithms can predict the missing parts of a fossil based on existing data, creating a more complete picture of ancient species. These reconstructions can be used to create 3D models, which can be studied and shared with researchers worldwide.

### Genetic Analysis and Ancient DNA

The analysis of ancient DNA (aDNA) has become a crucial aspect of paleoanthropology, offering direct insights into the genetic makeup of our ancestors. AI is set to revolutionize this area by enhancing the accuracy and efficiency of genetic analysis.

#### 1. AI-Driven Sequencing

AI algorithms can improve the accuracy of DNA sequencing, particularly when working with degraded or contaminated samples. These algorithms can identify and correct errors in sequencing data, providing more reliable results.

#### 2. Comparative Genomics

AI can also be used to compare aDNA with modern human genomes. Machine learning algorithms can identify genetic similarities and differences, shedding light on the evolutionary relationships between ancient and modern humans. This analysis can reveal how certain genetic traits have evolved and spread through populations over time.

### Fieldwork and Excavation

AI is not limited to laboratory settings; it is also making its way into the field. AI-driven technologies can assist in excavation and fieldwork, making these processes more efficient and less invasive.

#### 1. Remote Sensing and Drones

Drones equipped with AI-powered remote sensing technology can survey archaeological sites from the air, identifying areas of interest that may contain fossils or artifacts. This approach can reduce the need for extensive ground surveys and help researchers focus their efforts on promising locations.

#### 2. Robotic Excavation

AI-driven robots can assist in the excavation of delicate fossils. These robots can be programmed to carefully remove soil and debris, reducing the risk of damaging valuable specimens. Additionally, robotic systems can operate in harsh or inaccessible environments, expanding the range of potential excavation sites.

### Educational Outreach and Public Engagement

AI’s impact on paleoanthropology extends beyond research; it also has the potential to transform educational outreach and public engagement. AI-powered tools can make the field more accessible and engaging to a broader audience.

#### 1. Virtual Reality (VR) and Augmented Reality (AR)

AI can enhance VR and AR experiences, allowing users to explore ancient landscapes and interact with digital reconstructions of fossils. These immersive experiences can be used in educational settings to teach students about human evolution and in museums to engage the public.

#### 2. Interactive Platforms

AI can power interactive platforms that allow users to explore paleoanthropological data. These platforms can include features such as virtual excavation sites, interactive timelines of human evolution, and AI-driven chatbots that answer questions about ancient humans. Such tools can make learning about paleoanthropology more interactive and engaging.

### Ethical Considerations and Challenges

While the integration of AI in paleoanthropology holds great promise, it also raises important ethical considerations and challenges. Researchers must navigate these issues to ensure that AI is used responsibly and ethically.

#### 1. Data Privacy

The use of AI in genetic analysis raises concerns about data privacy. Researchers must ensure that genetic data, particularly from indigenous populations, is used with appropriate consent and protection. Ethical guidelines and regulations must be established to govern the use of genetic data in paleoanthropological research.

#### 2. Bias in AI Algorithms

AI algorithms can inherit biases present in the data they are trained on. In paleoanthropology, this could lead to skewed interpretations of human evolution. Researchers must be vigilant in identifying and addressing potential biases in AI algorithms to ensure accurate and unbiased results.

#### 3. Accessibility and Inclusivity

The use of AI in paleoanthropology should be inclusive and accessible to researchers worldwide. Efforts must be made to ensure that AI tools and technologies are available to researchers in developing countries, promoting global collaboration and knowledge sharing.

### Conclusion: A Transformative Decade Ahead

The next ten years promise to be a transformative period for paleoanthropology, driven by the integration of AI technologies. From automated data analysis and enhanced imaging to genetic analysis and robotic excavation, AI is set to revolutionize the field, offering new tools and insights that will deepen our understanding of human evolution.

As researchers navigate the ethical considerations and challenges associated with AI, they must strive to use these technologies responsibly and inclusively. By doing so, they can unlock the full potential of AI to uncover the secrets of our ancient ancestors and share this knowledge with the world.

The future of paleoanthropology is bright, and AI will undoubtedly play a central role in shaping its direction. As we embark on this exciting journey, we can look forward to a decade of groundbreaking discoveries and advancements that will forever change our understanding of human history.

Note – this was written by ChatGPT – 4o

Rockin’ with Dr. Mazel: Decoding Ancient Art in Africa and Beyond

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I know you will learn something and enjoy!

Until next time!

WTH

Paleoanthropology, the study of human evolution and our ancient ancestors, continues to be a fascinating field with ongoing discoveries and advancements.

Let’s explore some recent developments and potential future directions:

1. Genetic Insights:

• Advances in DNA sequencing technology have allowed researchers to extract and analyze ancient DNA from fossils. For instance, in 2022, a team led by Laurits Skov and Benjamin Peter from the Max Planck Institute for Evolutionary Anthropology sequenced nuclear, mitochondrial, and Y-chromosome DNA from Neanderthal individuals¹[1].
• These genetic studies provide insights into our evolutionary history, relationships between ancient hominins, and even family dynamics among Neanderthals.

1. Cutting-Edge Imaging Techniques:

• Modern paleoanthropology benefits from state-of-the-art imaging technology, 3D modeling, and virtual reconstruction. These tools allow scientists to examine fossils in unprecedented detail²[2].
• High-resolution scans help reveal hidden features, such as dental structures or cranial anatomy, shedding light on our ancestors’ lives.

1. Diet and Behavior:

• Researchers continue to investigate the diets and behaviors of early humans. Recent discoveries have challenged assumptions about meat consumption and brain evolution.
• For example, a study in 2022 questioned whether increased meat-eating directly correlated with larger brains. It turns out that the relationship is more complex than previously thought¹[1].
• Additionally, evidence of early cooking practices has been pushed back to around 600,000 years ago, suggesting that our ancestors were using fire to cook fish¹[1].

1. Environmental Context:

• Paleoanthropologists are increasingly interested in understanding the environments in which our ancient relatives lived. Climate, vegetation, and landscape play crucial roles in shaping human evolution.
• By combining fossil evidence with geological and ecological data, researchers gain a more holistic view of our ancestors’ lives.

1. Discovery of New Species:

• The field remains dynamic, with ongoing excavations and fossil discoveries. In 2023, intriguing findings included a 300,000-year-old chinless jawbone from eastern China that displays both modern and archaic features³[6].
• Such discoveries challenge existing species classifications and expand our understanding of human diversity.

1. Interdisciplinary Approaches:

• Paleoanthropology increasingly integrates multiple disciplines, including archaeology, geology, paleoecology, comparative anatomy, and experimental biology.
• Collaborative efforts enhance our ability to reconstruct the past and address complex questions about human origins.

1. Speculation on Posthumanity:

• While not strictly scientific, speculative works like Arthur C. Clarke’s “2001: A Space Odyssey” explore the prehistory of posthumanity. These imaginative narratives provoke thought about our future evolution⁴[4].

In summary, the future of paleoanthropology lies in continued interdisciplinary research, technological advancements, and the discovery of new fossils. As we uncover more about our ancient past, we gain deeper insights into what it truly means to be human. 🌟¹[1] ²[2] ³[6]

Source: Conversation with Bing, 5/2/2024
(1) Fourteen Discoveries Made About Human Evolution in 2022. https://www.smithsonianmag.com/smithsonian-institution/fourteen-discoveries-made-about-human-evolution-in-2022-180981344/.
(2) How New Tech for Ancient Fossils Could Change The Way We Understand …. https://www.smithsonianmag.com/innovation/new–tech-ancient-fossils-180951647/.
(3) A new human species? Mystery surrounds 300,000-year-old fossil – Nature. https://www.nature.com/articles/d41586-023-02924-8.
(4) Paleoanthropology of the future: the prehistory of posthumanity in …. https://research.monash.edu/en/publications/paleoanthropology-of-the-future-the-prehistory-of-posthumanity-in.
(5) 1 The Past, Present and Future of CHAPTER Paleoanthropology – Wiley. https://catalogimages.wiley.com/images/db/pdf/9781444331165.excerpt.pdf.
(6) Thirteen Discoveries Made About Human Evolution in 2023. https://www.smithsonianmag.com/smithsonian-institution/thirteen-discoveries-made-about-human-evolution-in-2023-180983512/.

Introduction

During the Pleistocene epoch, the world was full of human species, all throughout Africa, Europe, and Asia, and eventually, North America. Human species were interacting with, living with, and even breeding with each other. Some had vast continent-wide homes, while some migrated far away into new unexplored lands, such as obscure islands in Indonesia or the Philippines. It was a fascinating time, and is one heavily studied by anthropologists today. There is lots of fossil and genetic evidence providing clear pictures of most of these species, but there are also many gaps in our knowledge. 

The many fossils we have are very useful for understanding this time in human history, but also can cause lots of confusion, mainly in terms of taxonomy. In a previous article (https://worldofpaleoanthropology.org/2023/08/23/understanding-the-muddle-in-the-middle-hominins-from-the-pleistocene-guest-post-by-mekhi/), I discussed the Pleistocene hominins from Europe and some from Africa, and the confusion that comes with them, but recent research has added more confusion to the other species, this time living farther east, in Asia.

There were many hominin species in Asia, and they arguably cause more confusion than what is seen in Africa and Europe. To understand this, we first need to go through all the known human species from the area.

Hominin Diversity and Distribution During the Pleistocene of Asia

Animals often have large geographical ranges, and live in more than one place. Leopards (Panthera pardus) for example, have a huge range, mostly living in Africa, but also living in Europe and Asia, having the biggest range of any big cat today. Some species of humans had similarly large ranges. Obviously, Homo sapiens today have a massive range, living pretty much across the whole globe, but even other extinct species had large ranges as well. It is important to note a big difference between humans and leopards in this comparison though, which is that though leopards have a broad geographic range, the species is split into different subspecies in different areas, whereas other extinct human species are typically not.

A good example of broad geographic ranges is Homo heidelbergensis from Africa and Europe, though there has been contention on whether the African populations were the same species or not. Another species, one more relevant to this topic, is Homo neanderthalensis, or the Neanderthals, known from both Europe and (sparsely) from Asia.

Neanderthals in Asia 

Neanderthals were mostly settled in Europe, but were also present in Asia, mainly western Asia and the middle east, but sites containing their remains are also known farther east from Russia. Because it can sometimes be tricky to identify whether a specimen actually belonged to a Neanderthal or not, especially one so far from home, genetic analysis is often used. Genetic research on hominin remains in Russia shows that Neanderthals were present as far as the Altai region of Siberia. 

A cave called Chagyrskaya in this region is very famous for Neanderthals. This site, dated to ~60,000 years ago (kya), is not only a great example of the Neanderthal remains in Asia, with many tools, Neanderthal bones, and bones of other animals are known from it, but it is also a prime spot for Neanderthal genetics. 

Genetic research has shown that this population was relatively isolated, and had less than 60 individuals present, which is still large for Neanderthal standards. The genetic material from this cave is also exceptionally well preserved. The genome of one individual was sequenced for example, showing that she was female and closely related to the other known Neanderthals from western Asia.

Another cave, very close to Chagyrskaya, also documents Neanderthals in Russia; it is known as Okladnikov cave. Nearby to both these caves, housing a very unknown species only found in Asia, is Denisova cave, known for the Denisovans. 

Denisovans 

The Denisovans were a species of late genus Homo, very similar to Neanderthals, that lived in east Asia ~500-40 kya. Though our knowledge about this species is still growing, they’re still a cause of great confusion, mostly due to the fact that we have very, very few fossils. We have no skeletons, no skulls, nothing, just a few teeth and bone fragments. Almost everything we know about them is known just from genetic material. What we actually can learn about Denisovan morphology comes mostly from the dental remains.

The morphology seen in Denisovan teeth is mostly unique from that of Neanderthals and Homo sapiens, showing their designation as a separate species. The teeth do show similarities with Asian Homo erectus, but the overall morphology is mostly unique.

Though the Denisovans were most likely a distinct species, no true species name has been given due to the lack of fossil material. Species names like Homo altaiensis or Homo denisova may be used in the future.

The Asian Neanderthals and Denisovans also inhabited the same region, at around the same time. Neanderthals and Denisovans were sister species, and shared a recent common ancestor that was itself a sister species to Homo sapiens. Similar to how people can have some levels of Neanderthal DNA within their genomes, people today can also have some Denisovan DNA, with present-day Melenesians having up to 4-6% Denisovan DNAin their genomes. Much of the genetic material we do have of Denisovans to compare this comes from the few physical remains we actually have from them.

Denisovan genetic material is known from multiple remains. The most important and famous example of this may be the individual known as “Denny”. This individual, known from the fragmentary ‘Denisova 11’ remains, has very well preserved genetic material. From these remains, we know the sex of this individual, which is female, her eye color, which is brown, and most importantly, who her parents were. Her father was a Denisovan, but her mother was a Neanderthal, making her a hybrid. She also was ~13 years of age. 

This shows that not only were Neanderthals living with and interacting with Denisovans, but they were also breeding with them. This suggests that Neanderthals were in this region by 120 kya, even as old as potentially 190 kya. Very little is known about Denisovan biology, but more is known about their culture. 

Evidence of fire use, mainly charcoal and ashes in the sediments, has been found in Denisova cave, suggesting these people were using fire, which isn’t very surprising. Stone tools have also been uncovered in the cave, giving insight to their technology. Multiple stages of occupation can be found from these tools, each from the different and distinct sedimentary layers containing different tool assemblages from different times. Layers 11.3, 13, 14, and 15 come from the middle paleolithic, and layers 11.1 and 11.2 from the upper paleolithic. 

Also from the upper paleolithic layers, specifically the initial upper paleolithic, are lots of bone tools and decorative ornaments. These bone tools consist of an eyed needle and awe from the bones of large mammals. The bone ornaments, or jewelry, include beads, pendants, plaques, rings, a button/fastener, and decorated bones and bracelets. 

These bone tools show that the Denisovans were smart, and could take advantage of multiple resources. It also shows that they were culturally advanced, and could make jewelry, though simple, to decorate their bodies. It has long been thought jewelry was something unique to modern Homo sapiens, but we now have evidence that other human species including both Denisovans and Neanderthals were doing it too.

The Denisovans were and still are an odd and confusing species, but more species were causing more confusion down in southeast Asia at this time. One such species was Homo floresiensis, also known as the ‘hobbit’ species.

Homo floresiensis

Homo floresiensis at first sounds like a normal hominin species, living on the island of Flores in Indonesia from ~190-50 kya. This species was one of the Pleistocene hominins in Asia, along with Neanderthals, Denisovans, and all the other species that will be discussed later, but there is something unique, and very confusing about this species. 

Though very human-like, clearly in the genus Homo, this species was very primitive, especially in the fact that the adults were only ~1 meter (~3 feet) tall. This short stature of this strange species has caused great confusion, and a few different hypotheses have been proposed to explain it. 

At first, the fossils, found in Liang Bua cave, were interpreted as pathological modern humans, humans who suffered from microcephaly (a decrease in the size of the head). However, this hypothesis was very quickly shown to be false. The skull of H. floresiensis and that of a microcephalic human are very different, and H. floresiensis lacks the expected features for a person with this condition. This gave a need for new hypotheses. H. floresiensis clearly wasn’t a modern human, nor was it ancestral to modern humans; it was a strange ‘hobbit’ species living on a secluded island in Indonesia.

This idea of an off-branching species was very important at the time; it was commonly thought that human evolution was a straight line of progression, with the only branching members of the lineage being groups like the robust australopiths (Paranthropus) and Neanderthals. This species showed the true diversity of hominins that lived before modern humans that weren’t actually ancestral to modern humans. 

The next hypothesis for the origins of these hobbits was that they were a subset of Homo erectus, a species that inhabited the nearby island of Java at the time, that simply suffered from insular dwarfism, a common evolutionary phenomenon that occurs when species are trapped on isolated islands with limited resources. This would explain why H. floresiensis was so short and why it was there, but it would not explain the rest of the morphology.

Even early on in the research of H. floresiensis, scientists noticed that the species had many basal, or primitive characteristics, traits shared with earlier African hominins such as Australopithecus and early Homo. Some of the obvious primitive traits include its short stature, but it also had a small brain volume (~380 cubic centimeters), and limb proportions similar to that of earlier hominins. However, it still had some derived features shared with later species like Homo erectus, such as a flatter, more orthognathic face, and more derived teeth. 

Cladistic analysis suggests that H. floresiensis arose sometime around the time of Homo habilis and Homo rudolfensis, the two earliest known members of the genus Homo, though it is possible that it came sometime after early Homo. The origin of H. floresiensis is still highly debated; both ideas are very plausible and have support, but the main consensus right now seems to be that this species is a descendant of early hominin species from Africa, and just happened to end up nearby to where H. erectus would inhabit.

This however does bring up another question, the question of how this species even got to the island in the first place. Flores is an island, and has not recently been in contact with other land masses, unlike other Indonesian islands like Java. This means that H. floresiensis had to cross some waterways to get there. This isn’t actually too implausible. Much of the native wildlife of the island, from mammals to reptiles, seem to have come to the island from neighboring islands, such as Java, Sahul, and Sulawesi. Some of the larger animals, such as large reptiles and the extinct elephant relative Stegodon likely could have swam or even floated, while the smaller mammals, such as rodents, may have rafted there. These are all also species that H. floresiensis ate and butchered. 

This rafting hypothesis easily applies to H. floresiensis. We can never know the true path the hobbits took to get there, but they very well may have rafted, likely unintentionally, to the island they would call home. They would have a long time of success on the island after their arrival, but went extinct at some point, and their extinction offers even further confusion. 

Natural disasters, such as tsunamis and volcanic events are common there, and definitely had effects on them, but they don’t seem to have wiped them out. A large volcanic eruption is known to have occurred on Flores ~12 kya, but this was too late in time, as H. floresiensis seems to have been extinct by this point. Their disappearance seems to have occurred ~50 kya, which matches exactly with the known arrival date of Homo sapiens on the island. 

For a brief period, our species seems to have coexisted with the hobbits, and unfortunately, we may have led to their extinction. The origins and disappearance of these hobbits adds more confusion to what already was a confusing time and place, but they weren’t the only confusing species in the area.

Homo luzonensis 

While Homo floresiensis was living in Indonesia, another confusing species was living nearby in the Philippines, called Homo luzonensis. Similar to the Denisovans, H. luzonensis is known from very little fossil material, though we have more from this species than we have from the Denisovans. Unlike the Denisovans however, we have no genetic material from H. luzonensis. No full skeletons have been found either, unlike H. floresiensis. Only 13 remains dated to 67 kya have been uncovered. Overall, very little is known about this species. 

The remains from this species include mostly teeth, some finger and toe bones, and the femur of  a young child. All the remains come from the same stratigraphic layer of Callao Cave, in the island of Luzon. Though very small in numbers, the fossils we do have can tell us some things, or at least give us hints. The teeth may be the most useful of the remains for learning about this species.

Out of the 13 remains, 7 of them were teeth, 5 of which seem to have belonged to the same individual. These 5 teeth make up the holotype of the species, another reason why they have a species name and the Denisovans don’t. The teeth are primitive and small, and similar to those of H. floresiensis.

The small size of the teeth suggests that H. luzonensis may have had a small body size, as tooth size often reflects body size, though this isn’t always the case. The metatarsals and metacarpals in the feet and hands are also very small and primitive, resembling H. floresiensis and early members of the genus like Homo habilis. Despite the size of the teeth, they also share many traits with Homo erectus. This could suggest that H. luzonensis descended from H. erectus and potentially suffered some insular dwarfism, though it is possible that it was a descendant of earlier hominins, like what is thought for H. floresiensis.

Like H. floresiensis, the origins of H. luzonensis are unknown and heavily debated, though, also like H. floresiensis, whoever they descended from, they likely got to the island via rafting, as Luzon has never been recently in contact with any other landform. If not from earlier hominin species, these two island based human species must have descended from H. erectus, the only other hominin species living in the area.

Homo erectus

Homo erectus was perhaps the most successful human species, at least for its time. The oldest H. erectus fossils are known from 1.8 million years ago (mya), to as recent as ~100 kya. H. erectus arose out of Africa, and migrated all throughout Eurasia, settling mostly in southeast Asia. 

The site known as Sangiran, in the Solo basin on the island of Java Indonesia has revealed over 40 H. erectus specimens, making it perhaps the most important locality for H. erectus in Indonesia. Sangiran is one of the 3 main sites known for Homo erectus remains in Eurasia, with the others being Dmanisi in eastern Europe and Zhoukoudian in China. The earliest of these fossils in Indonesia are about 1.5m years old, which is very close to the 1.8m years old remains in Dmanisi, the oldest H. erectus remains out of Africa. This shows that they spread and migrated very quickly.

This population in Indonesia however lived for a very long time after that; they’re seemingly the last surviving group of H. erectus. 12 H. erectus skull caps, along with 2 leg bones, uncovered from Ngandong, central Java, near the Solo River, represent the last known H. erectus population to have lived, along with the most derived population. These fossils lived between 117-108 kya, showing truly just how long H. erectus lived as a species. 

This brings up the question of how did H. erectus reach Java in the first place? The answer to that is glaciation. During the Pleistocene, as old as 2.6 mya, glaciations resulted in drastic drops in sea level, as much as 72-120 meters (~236-393 feet) below current sea level in some cases. This resulted in many land bridges across Indonesia, allowing for faunal migration to the islands. This led to the colonization of Java by many different animals by about 2 mya, including mammoths and likely H. erectus, though it is likely that they still had to cross some water bodies to get there.

When they arrived at the island, they were introduced to an environment of moist grasslands and open woodlands, with riverine landscapes and large streams, along with long annual dry seasons. Aside from Indonesia, H. erectus is also commonly known from China, mainly at a site called Zhoukoudian. 

Zhoukoudian represents ~80 individuals, the most number of H. erectus individuals known from anywhere, along with ~100,000 stone tools. This population arrived there long after others arrived in Indonesia, living there from ~750-200 mya, though their occupation there seems to have been sporadic. 

Unfortunately, by 108k years, the all-mighty Homo erectus had gone extinct. It is hypothesized that their extinction was caused by climate and environmental changes in the region. The vast and open environments they migrated into, found in both Indonesia and China, transitioned to a wet and crowded rainforest, which may have ended their reign. However, we likely will never know what truly wiped them out, as it is hard to point at the exact causes of small extinctions. 

H. erectus is the cause of little confusion, being one of the better understood species from the Pleistocene. However, there was another human population living in China that is incredibly unknown, unique and confusing, more so than any of the other species of the time, making the name the ‘muddle in the middle’ especially well deserved.

Homo longi

The next species in Asia is called Homo longi. This species is the most recently named human species, being first described in 2021. Even though it was first described in 2021, the skull, known as the Harbin skull, was originally discovered in 1933 during a construction project in the Hebei Province of northern China, although the exact locality is unknown. The skull was dated to ~146 kya.

The skull itself is one of the most well preserved hominin crania from the Pleistocene of Asia; it is only missing most of its teeth and possesses damage to its left zygomatic arch. It is also very large. It has a large cranial capacity of ~1,420 cubic centimeters. Some of its morphology is similar to that of Homo sapiens, such as its large cranial capacity, short face, and small cheekbones, but it also possesses some other unique morphology. This includes a low cranial vault, pronounced brow ridges, large molars, and alveolar prognathism below the nose.

It also shares features with Homo heidelbergensis and Neanderthals. This is a unique and strange combination of traits. This set of traits is also seen in other hominin crania from China, that seem to represent a unique and unknown human population or species living in China during this time, that includes Homo longi. As it turns out, there is a lot of hominin fossil material from the Pleistocene from all throughout China, and these fossils are the most confusing part of human evolution in the Pleistocene of Asia. 

The Mysterious Hominins of Pleistocene China

Much of the hominin fossil record of Pleistocene China, just as it is as a whole, is teeth. Below is a chart showing different locations in China where hominin teeth were uncovered, spanning a temporal range of 990-15 kya.

Location of Discovery	Dating	Number of Teeth
Meipu, southern China	990-780 KYA	4
Yiyuan, eastern China	770-126 KYA	7
Longtan, Cave, Hexian, eastern China	412 KYA	10
Panxian Dadong, southern China	300-130 KYA	4
Tongzi, southern China	172-240 KYA	4
Luna Cave, southern China	126-70 KYA	2
Dushan Cave, southern China	15 KYA	1

Only a few of the dental remains have been assigned a species, such as the teeth from Luna cave, which clearly belong to Homo sapiens. The morphology of these teeth is also interesting. Many of the teeth have Homo erectus-like features, while other traits appear more modern. This mosaic morphology in the dentition is similar to the mosaic morphology of the rest of the bodies, especially the skulls. 

This mosaic nature, the mix of archaic and modern features has caused some to suggest that many of these remains belong to hybrid individuals, hybrids of archaic and modern human species, such as H. erectus and H. sapiens. This idea has especially been proposed for some of the postcranial material that has been uncovered, mainly femora.

The skulls from this time and place, as mentioned, also display strange morphology, and have been under great research lately, revealing a lot about the hominins living in China. A collection of well preserved hominin crania, including the Harbin skull of Homo longi, make up the best set of hominin remains from this time, and are the most useful and important. Well preserved hominin crania are known from 5 sites, Harbin, Dali, Jinnisuan, Maba, and maybe most importantly, Hualongdon.

Dali

The Dali skull, from the Shaanxi Province of northwest China, was originally uncovered in 1978. This skull has been estimated to be ~200k years old. The specimen is mostly complete, only having some distortion and a few missing pieces, including a big chunk of the parietal bone.

The face of the Dali skull resembles that of Homo sapiens, but aside from the face, the skull resembles other African and eastern Eurasian Pleistocene hominins. Overall, it most greatly resembles the skulls of early H. sapiens of north Africa and the Levant region. This combination of traits from multiple hominins is a consistent trend throughout all these skulls. 

The Dali skull may show that during the Pleistocene, many different human species and populations in Asia were breeding with one another, creating a ‘braided stream’, with gene flow from different groups creating unique morphology in different populations. At its extremes, this idea is known as the ‘multiregional hypothesis’, and is in contention with the theory of ‘out of Africa’.

Jinniushan

The next important specimen is not not just a skull, but a whole partial skeleton and cranium from northeast China. This is very rare in the hominin fossil record from this time, as most specimens are either just a skull, or fragmentary remains like teeth or small postcranial (body) material. This is not the case for the Jinniushan specimen, which consists of a skull, along with an arm bone (left ulna), a pelvic bone (left innominate), 6 vertebrae, ribs, and bones from the hands and the feet. 

The skull itself is fairly complete, but was broken during its excavation in 1984. What is missing from the skull is mostly from the frontal, parietal, and occipital regions. The dating of this specimen has been somewhat controversial, but current estimates place it at roughly ~200 kya, similar in time to Dali. Other fossils come from the same strata as the Jinniushan specimen, including bears, wolves, deer, and rhinos.

Morphologically, the skull shares some similarities with Dali, along with a mix of Homo erectus and Homo sapiens features. They both possess a small mastoid process, similar parietal bones, and a shared location of the maximum cranial breadth. There are many differences too, including smaller brow ridges, a shallower supraorbital sulcus, etc. The cranial capacity of the Jinnushan skull is roughly 1,400 cubic centimeters, which is very large, and around the same size as modern H. sapiens. 

The presence of well preserved postcranial material provides a rare case in which the encephalization quotient (the size of the brain compared to the body) can be seen. In Jinniushan, the encephalization quotient is 4.15, which is very close to the predicted encephalization quotient for other pleistocene hominins from this area. As for the rest of the body, this individual’s body mass was estimated to be 78.6 kg (~172 lbs), and the body height to be 168 cm (~5 ½ ft). It also had shorter limbs than expected. 

All these body proportions are consistent with adaptations for colder weather, in which species adapt to be larger and have shorter limbs to conserve body warmth. This is known as Allen’s rule, and is also seen in other hominin species such as Neanderthals. The climate in China during the Pleistocene is not extensively studied, but research has revealed a climate transition, known as the Mid-Pleistocene climate transition (MPT), characterized by increased monsoon and glaciation cycles from ~1.2m to 700 kya. This occurred before the Jinniushan specimen was around, but the presence of these features may suggest similar conditions during its time. 

The foot of the Jinniushan specimen is also interesting. It possessed some derived features, such as an increased stability of the medial longitudinal arch, but it also had several primitive features, such as lower arches and a less stable hallucal metatarsophalangeal joint. These traits provide a glimpse into the stride of this pleistocene hominin; they suggest that this individual had a slightly different stride than what is seen in modern H. sapiens.

Other details about the Jinniushan specimen include that it was likely female based off of the pelvis, and was ~16-20 years of age, making her relatively young. Stone tools and traces of fire have also been reported alongside the Jinniushan specimen. 

Maba

After Jinniushan in this skull set comes the Maba skull. This skull, from ~300-130 kya is very fragmentary, consisting of a skull cap, a right orbit, and a portion of the nasal bone. Along with this, it possesses pronounced brow ridges and a heavily curved frontal bone, more so than Chinese Homo erectus. The brow ridges are also similar in shape and size to European Neanderthals. 

The thickness of the cranial vault is also similar to that of modern Asian Homo sapiens. Just as with all the other crania discussed so far, Maba possesses a strange mosaic of features shared between multiple other hominin species. It is also somewhat unique from Dali and Jinniushan, having a more prognathic face. The cranial capacity of Maba is about 1,300 cubic centimeters, within the ranges of Homo heidelbergensis, Neanderthals, and H. sapiens. There are a few other hominin remains aside from the cranium as well, consisting of 5 teeth and a partial mandible, though they seem to not be associated with the Maba cranium, as they dated to ~237 kya, and some of the teeth are associated with H. sapiens instead.

The last strange skull that will be discussed is one of the more recently described specimens, like Harbin. It may be one of the more important specimens known from this time and place; it is the HLD6 Hualongdong skull.

Hualongdong 

The taxonomic placement of all these skulls is very confusing. They’re all unique in their own ways, and all have mosaic characteristics, combining multiple traits from several other hominins. One commonly thought idea is that these skulls, or at least for some of them, are Denisovans. They’re in the right place and time, but this could never be confirmed. 

We have no confirmed Denisovan cranial material; there is nothing to definitively back up the claim that these Chinese skulls represent Denisovans, and no genetic material from these specimens to compare. There is the Denisovan partial mandible, Xiahe, but no cranium, and all of the skulls discussed here are crania, but have no associated mandibles, at least up until Hualongdong. 

The specimen known as HLD 6, from Hualongdong eastern China, is a ~300k year old juvenile hominin skull and mandible, along with some dental remains. The skull’s face resembles that of other Asian hominin crania, including Dali, Jinniushan, Maba, and even Homo erectus. The face of the skull is very flat, like Homo sapiens, though this could also be because the individual was young, only ~13-15 years of age; face shape changes lots in hominin ontogeny. Overall, the cranium fits in well with the other mosaic skulls from this time and place. However, the mandible is the more important part of the specimen. 

The mandible is broadly characterized by a robust mandibular corpus (the body of the mandible), and a more gracile mandibular symphysis and ramus (the front and back ends of the mandible). It also lacks a chin, showing that it can’t belong to H. sapiens. It does however share many other traits with other pleistocene hominin mandibles, including a pronounced alveolar planum, a superior transverse torus, a pronounced endocondyloid crest, and a well-developed medial pterygoid tubercle. 

It shares lots in common with other Pleistocene hominins from throughout Eurasia. This is significant as it is one of the only complete hominin mandibles from China, only going alongside Penghu 1 from Taiwan (~190-10 kya), Xujiayao 14 from northern China (~120 kya), and the Denisovan Xiahe mandible (~160 kya). 

Despite also being from China, the HLD6 mandible differs greatly from these other mandibles. This is significant as no other of the Chinese crania discussed so far also have associated mandibles. Because the HLD6 cranium is so similar to the other crania, it is reasonable to assume that its mandible is similar as well. If the mandibles are similar, it means that all the mandibles are distinct from the other Chinese mandibles. 

This is especially important for the Xiahe mandible. If the Xiahe mandible is distinct from the other mandibles, then the cranium may be too. This could imply that the Denisovan cranium and these other Chinese crania are distinct, showing that these hominins may not be Denisovans. This especially applies to Homo longi, as it has been long speculated to be Denisovan. This could be a huge discovery, but it is very important to note that this claim is entirely based on logical speculation, and will need significant further, physical evidence to be proven.

What Are These Skulls?

So now we know what the skulls (probably) aren’t, what exactly are they? These fossils are clearly not modern Homo sapiens, and also shouldn’t be grouped in as Homo erectus either, despite its presence in the region at this time. One species that these hominins have sometimes been grouped under is Asian Homo heidelbergensis. 

Homo heidelbergensis already has had a history of confusion when it comes to many specimens being grouped into it that may not necessarily belong there. Though many of the African and European hominin specimens fit into H. heidelbergensis, the Asian specimens seem to be overall distinct.

The 2 main reasons why these Asian specimens are sometimes grouped into H. heidelbergensis are 1) some apomorphic (derived) traits seen in Asia are also found in European H. heidelbergensis, and 2) Homo sapiens didn’t descend from Asian Homo erectus, so it must be H. heidelbergensis instead. 

Some of the shared traits include very heavily increased encephalization, and the presence of canine fossa, which is found in several of the Chinese specimens and also the fossils from Gran Dolina Spain, associated with Homo antecessor. This shows that the Chinese specimens may represent a group closer to H. heidelbergensis cladistically, and farther from H. erectus. 

However, despite these shared traits, there are many distinguishing traits as well. These traits include the orientation of the frontosphenoidal process of the zygomatic bone, the upper facial height, shovel shaped incisors, the presence of interparietal bones, and agenesis of the 3rd molars. Some H. heidelbergensis do possess some of these traits, such as interparietal bones, but they’re uncommon.  

Overall, it is unlikely that the Chinese specimens represent H. heidelbergensis, but they may be related to it. Another common idea for the classification of these specimens is placing them in a new species. Homo longi is the only one of the Chinese crania that has an actual assigned species, but other species names have been proposed for other specimens, such as Homo daliensis and Homo mabaensis. This however, is counterproductive; the Pleistocene is already very confusing in terms of hominin taxonomy with lots of very confusing taxa; adding more taxa will only muddle it up more.

It might not be terrible to group them all under one diverse species, such as M. mabaensis, but all this would do would be changing what we call the fossils, and wouldn’t do much for our actual understanding. It has been proposed that the safest course of action in terms of what to call these specimens is simply to refer to them as archaic Homo sapiens until further analysis clears up the muddle in Asia.

Conclusion

This mysterious group of hominins clearly were a distinct group, likely closely related to H. heidelbergensis and other Pleistocene hominins. Classifying these hominins is difficult, as there isn’t any consistent set of traits that define them. The only truly defining trait is the increasing morphological diversity throughout all of them. It is also unknown how these hominins ended up where they did. There are 3 hypotheses for how they got to China, but nothing for certain. 

The first idea is that they got there via the Chao Phraya river basin; the second is that they got there through east Vietnam, and the 3rd and last idea is that they traveled along the coast of southern Asia and Myanmar. These are all plausible ideas, but none of them have enough evidence to back them up to make them certain. 

Until more evidence and research comes along, the Pleistocene of Asia will remain confusing, and, just like with Europe, further research and discoveries, such as new fossils and genetic evidence are our best hope to resolve this confusing time. 

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64. Sáez, Roberto. “A new sister group of the sapiens lineage: on the skulls of Hualongdong and Harbin”. Nutcracker Man, 10-25-21. https://nutcrackerman.com/2021/10/25/nuevo-grupo-hermano-linaje-sapiens-craneos-hualongdong-harbin/ 
65. Bae, J. C. (2010). The late Middle Pleistocene hominin fossil record of eastern Asia: Synthesis and review. American Journal of Biological Anthropology, 143(S51): 75-93.  https://doi.org/10.1002/ajpa.21442
66. Liu, W., Athreya, S., Xing, S., Wu, X. (2022). Hominin evolution and diversity: a comparison of earlier-Middle and later-Middle Pleistocene hominin fossil variation in China. Philosophical Transactions of the Royal Society B, 377(1848). https://doi.org/10.1098/rstb.2021.0040

Sometimes AI can be fun, and hearing things in someone else’s voice can be one of those, especially if it’s how to explain something in a certain way.

I hope you enjoy this as much as I did.

“Ah, if I were Louis Leakey, I’d be quite fascinated by the modern interpretations of the Out of Africa theory. You see, when I began my work, we had but a glimpse into the vast expanse of human history. Now, the theory has evolved and expanded with new evidence.

The modern concept still holds that Homo sapiens originated in Africa and spread across the globe. However, recent studies suggest that this migration was not a single exodus but rather a complex series of dispersals over time¹².

One significant update to the theory is the recognition of interbreeding between modern humans and archaic hominins. It’s now understood that as Homo sapiens ventured out of Africa, they occasionally interbred with local populations like the Neanderthals and Denisovans². This paints a picture of a more interconnected prehistoric world than we once thought.

Furthermore, there’s evidence to suggest that the impact of migrations from Asia to Europe may have been stronger than those from Africa, challenging the notion of a purely African origin for all modern humans¹. Teeth morphology studies, for example, show distinct differences between African and Eurasian specimens, indicating a long period of independent evolution on both continents¹.

In essence, while Africa remains the cradle of modern humanity, the story of our spread and interaction with other hominins is far more intricate than I could have ever imagined in my time. It’s a testament to the ever-evolving nature of science and our understanding of human origins..”

Source: Conversation with Bing, 4/12/2024
(1) Is the Out of Africa Theory Out? | Scientific American. https://www.scientificamerican.com/article/is-the-out-of-africa-theory-out/.
(2) Out-of-Africa versus the multiregional hypothesis – Nature. https://www.nature.com/scitable/content/out-of-africa-versus-the-multiregional-hypothesis-6391/.
(3) Modern Humans Came Out of Africa, “Definitive” Study Says. https://www.nationalgeographic.com/history/article/modern-humans-came-out-of-africa-definitive-study-says.
(4) Out of Africa Theory in Evolution | Anthroholic. https://anthroholic.com/out-of-africa-theory.
(5) What is the ‘Out of Africa’ theory? – History Skills. https://www.historyskills.com/classroom/year-7/year-7-human-migration-reading/.
(6) undefined. http://bharatkalyan97.blogspot.in/2013/04/defining-meluhha-demise-of-dravidian.html.
(7) Getty Images. https://www.gettyimages.com/detail/news-photo/british-anthropologist-dr-louis-s-b-leakey-sits-at-a-table-news-photo/3233313.

Introduction

The natural world is very often seen as dark and violent, a ‘dog-eat-dog world’. Though this isn’t always an accurate representation of nature, it isn’t entirely false either. Predatory animals will hunt and eat whatever they need to survive, to the extent of what they can hunt. We humans often like to think that we’re safe from these dangers, that we’re above the other animals and aren’t in danger from other predators we share this planet with. However, even a deep look into this will show that this isn’t the case, and never has been.

Shark Attacks are rare today in humans, but not completely unseen. Roughly 10 people a year are killed in shark attacks worldwide. Oftentimes these are surfers, who the sharks mistake as seals or sea lions, an animal they do commonly hunt. Archaeological evidence of shark attacks are even rarer. However, one example was described in 2021.

Evidence of a 3,000 year old shark attack has been uncovered from Japan, going back to the hunter-gatherer Jōmon period of the Japanese archipelago. This individual’s remains, known as Tsukumo 24, were buried at the Tsukumo site near Japan’s Seto Inland Sea, where modern shark attacks are relatively common to this day. From their remains, 790 perimortem injuries were found, characteristic of shark attacks. These injuries include deep bone gouges, punctures, cuts, and blunt force fractures. Most of the damage was on their pelvis, legs, shoulder, and arms. Along with this, their left hand and right leg were missing. 

The right leg was present, but was upside down in the grave, and was not in articulation with the rest of the body. The distribution of the wounds suggest that the individual was alive during the attack, rather than being scavenged. The attack was fatal, and this individual was likely eventually killed due to blood loss and shock. The shark species responsible for the attack was most likely either a white shark (Carcharodon carcharias) or a tiger shark (Galeocerdo cuvier). Whatever remained of this individual’s body seems to have been retrieved and buried after. 

This is a good example of humans being hunted in recent archaeological history, but even today, humans aren’t safe from other predatory animals. 600-800,000 human deaths are caused by tigers in Asia every year.

In Some places in India, leopards are massive threats, killing more people than all other cats combined. African cats aren’t as much of a threat, with cheetahs almost never hunting people, and lions rarely (but not never) hunting people, but it is a big problem in Asia.

A big reason for why predation is decreased in modern humans is because of our shelter and technology, protecting us from these dangers. Our other primate cousins however, do not have these luxuries, and face many more dangers. Not just our modern cousins however, but also our extinct ancestors and relatives. Examples of predation upon our ancestors are very prevalent throughout the fossil record. 

The Predators of Extant and Extinct Primates 

One of the most common predators of primates today are leopards. In Ethiopia, 7 encounters were recorded over a span of 6 years between geladas (Theropithecus gelada) and leopards (Panthera pardus).

Actual predation was rare, only being observed 1 time, but interactions occurred multiple times, typically ending with fear responses from the geladas, including distress calls and fleeing. Predation is rare towards baboon species due to their large social groups, known as multilevel societies, in which there are many individuals present. This suggests that having large social groups is advantageous to keep away predators. This lines up with the tendencies of leopards to hunt galadas in smaller social groups. Leopard hunting has also been observed in olive baboons (Papio anubis) as well, along with vervet monkeys (Chlorocebus pygerythrus). 

Leopards hunt baboons most commonly at night. During the late Miocene to the Pliocene, around 3-7 million years ago, this would have provided a reason for our hominin ancestors to stay in the trees at night, to avoid these nocturnal predators. This didn’t save every hominin however. 

SK 54

The skull cap fragment of a juvenile Paranthropus robustus, an extinct hominin relative, was uncovered in 1949, in a South African cave called Swartkrans, dating to 1.8-1.3 mya. On the back of the skull cap, near the lambdoid suture of the occipital bone, there are two puncture marks, matching the bite marks of a leopard. It seems that this individual was dragged away by the head by a leopard.

In the same deposit as SK 54, the mandible of a leopard was uncovered, known as SK 349. The canines of SK 349 fit in perfectly to the punctures of SK 54.The species of leopard that did this was a modern leopard (Panthera pardus), the same species that hunts modern primates today. This species arose in Africa during the Pleistocene, and would very soon migrate out of Africa to colonize places throughout Eurasia, with only the African variants still around today. 

Off the ground, another predator of primates today and extinct hominins is the African crowned eagle. 

The Taung Child 

A very big threat to African primates are predatory birds, specifically the African crowned eagle (Stephanoaetus coronatus). These eagles are very powerful and capable of killing mammals larger than themselves, including baboons.

In a 37 month study from Ngogo, Kibale National Park, 81% of the kill samples were monkeys. Redtail monkeys (Cercopithecus ascanius) were especially common, making up 66% of the identifiable monkey remains. Other research from the Tai Forest has collected 1,200 remains of animals hunted by these eagles. 669 of these were primate remains.

These eagles leave consistent taphonomic signatures, making them easily identifiable. The hind limbs and cranial bones often preserve well, while other parts, such as the ribs, vertebrae, carpals, and tarsals do not. Understanding the taphonomy of modern primates caused by crowned eagles, we can identify when this was the cause of death for extinct primates. 

The skull of a juvenile Australopithecus africanus from South Africa, dating to 2-3.2 million years ago, who was about 3 years old when it died, unfortunately seems to have been killed by this species of eagle. 

This skull is very significant for understanding human evolution, especially the brain development of our early ancestors, but is also important for understanding how these species interacted with their environments, and the threats they faced there.

The skull, known as the Taung Child, possesses talon marks in its orbits, identical to those left by crowned eagles in modern primates. Scratch marks are also present on the rest of the skull, including the frontal, temporal, parietal, and occipital bones. It seems that the Taung Child was carried off by a predatory eagle, and was eaten in its nest, where the skull would fall to the ground and be preserved.

OH 8

Another very common predator in Africa are crocodiles. 

Crocodiles do hunt primates, but not as common as other large mammals. When they do hunt primates, they typically ambush them from the waters edge, just like what they do with other mammals. One example was observed in Indonesia in 1984.In this case, a juvenile crab-eating macaque (Macaca fascicularis) was ambushed by a crocodile when sitting at the edge of a river bank. This seems to be what happened to a juvenile Homo habilis.

The OH 8 specimen is a foot belonging to a subadult or juvenile Homo habilis, based on the fusion of the metatarsals. This specimen is very important for understanding the locomotion of Homo habilis, as the arches in the feet are very significant for bipedal walking.The specimen is also possibly associated with the OH 7 mandible and the OH 35 leg bone. More interesting however, is the evidence of a crocodile attack in these fossils. 

The foot, along with the possibly associated leg bone, bear extensive tooth marks indicative of a crocodile attack. The foot seems to have been disarticulated and torn from the rest of the body by the crocodile. The leg bone was found in a different deposit, and therefore may not belong to the same individual. 

The fossils come from the FLK 22 FLK NN 1 fluvial sediments from the Olduvai paleo lake bed from Tanzania, dating to 1.8 mya. The crocodile that hunted OH 8 could have been a modern species of crocodile, but also could have been one of the many extinct crocodile species from the area. During the Pliocene and Pleistocene, there was a great diversity of crocodilians. One example of this is a species of horned crocodile from Oldovai Gorge, Tanzania, right where OH 8 was discovered. This species is characterized by large triangular ‘horns’ over its ears, along with a deep snout.

This species is very similar to modern crocodiles in the genus Crocodylus. The fossils also date to 1.8 million years ago, right alongside OH 8.This is the largest species of crocodile in the area, and very likely was the species that hunted our ancestors who lived alongside it. 

Along with extinct crocodiles, there were many other extinct predators that are no longer alive today that would have been big threats to extinct hominins.

All the predators we’ve discussed so far, aside from the crocodile, are animals that are still alive today. However, there were plenty of animal species that our ancestors lived alongside that would have posed a major threat to them. 

Ancient Predators

Most of the extinct predators from eastern and southern Africa were carnivorans, mainly big cats, but also including hyenas, canids (dogs), genets, mongooses, and extinct predatory otters. One site in Kenya preserved remains of all these animals, including orolutra sp., Enhydriodon (2 species), Genetta sp., Helogale sp., Homotherium sp., Dinofelis petteri, Felis sp., and Parahyaena howelli, dating to aout 5.3 mya. Some of these species are still around today, and not all would have hunted our ancestors, but the carnivoran diversity of eastern Africa during the Pliocene is nonetheless clear.

Down in South Africa, in Cooper’s Cave, a cave site known for Paranthropus robustus remains, many carnivoran remains are known as well.

These include mostly felids, such as Megantereon, Dinofelis, Panthera, Acinonyx, along with the small genera Caracal and Felis. Some of the most dangerous species from this site include the saber-toothed cats, Megantereon, Dinofelis, and Homotherium.

The saber-toothed cats belong to the group machairodontinae, a very diverse and successful felid lineage. Basal (early) members of this group include Promegantereon, Machairodus, Nimravides, Dinofelis, Metailurus, while more derived members include Megantereon, Amphimachairodus, Homotherium, Xenosmilus, and most famously, Smilodon. 

The name eumachairodontinae has been proposed for these later species. Sub groups within this group include the tribes smilodontini, homotherini, and metalurini. The famous saber-teeth are exclusive to the later eumachairodonts, but other traits define the group machairodontinae as a whole. Multiple later machairodonts, or eumachairodonts, were in Africa at the same time as our earlier ancestors, and very likely hunted them.

Megantereon 

Megantereon was a species of machairodontid that lived throughout Afro Eurasia, and even as far as North America, dating from about 2-4.2 million years ago.This species possesses at least 3 species (M.‭ ‬cultridens,‭ ‬M.‭ ‬falconeri and M.‭ ‬whitei) but possibly contains up to 13 species.There has been debate on whether different specimens represent different species, or are just examples of sexual dimorphism.

Their size averaged at about 3 feet long, though it varies slightly between species.Megantereon possessed large upper canines, but not as large as other related species, like Smilodon, giving it the name the “dirk-toothed cat”.This genus was very large and robust, suggesting that it was an ambush predator rather than a pursuit predator like a cheetah. 

The species from Africa, Megantereon whitei, would have been the species that hunted our ancestors. Remains of this species are known mostly from Africa, though some fossils have been found as far as central Italy, showing evidence of faunal dispersal during the Plio-Pleistocene transition. Remains of African Megantereon, from northern Kenya dating to 3.5 mya, have been given the name Megantereon ekidoit, representing a possible second species of this genus in Africa.

Dinofelis

Another machairodont in Africa that lived alongside our ancestors was Dinofelis. Dinofelis is known from the same geographical range as Megantereon, dating from 5-1.2 mya. Belonged to the tribe metalurini, along with the other genera Metailurus, Adelphailurus, Stenailurus and Fortunictis.

There are up to 8 species of this genus, including D. cristata, D. diastemata, D. barlowi, D. paleoonca, D. darti, D. piveteaui, D. petteri, and D. aronoki, many of which come from Africa. The African species had a range from north Africa, all the way through down into South Africa. 

Caves in South Africa possess Dinofelis remains alongside other hominins like Australopithecus africanus and Paranthropus robustus. Dinofelis had teeth very similar to a modern cheetah, specialized for slicing through flesh. Very likely hunted the hominins it lived alongside. 

Homotherium

The last major big cat that hunted our ancestors is the infamous scimitar cat, Homotherium. Homotherium lived for the longest time out of the 3 big cats, living from 5 million years to 10,000 years ago, one of the most successful machairodonts. Along with a large temporal range, Homotherium had a great geographical range, living in the same places as Megantarion and Dinofelis. Later members of the species outside of Africa would have hunted large ice age mammals, like wooly mammoths, and even early Homo sapiens.

Homotherium was very large and robust, with powerful limbs and large teeth, and got up to 7 feet long, weighing 500 pounds.

Homotherium was a very diverse genus as well, with up to 15 species, such as Homotherium latidens, Homotherium ischyrus, Homotherium venezuelensis, and the African species, H. aethiopicum. Homotherium latidens is the species that would have interacted, and hunted modern humans throughout Eurasia.

Throughout the lifespan of this genus, it would have lived alongside our earliest ancestors, such as Australopithecus in Africa, all the way to modern humans in Eurasia, along with some of our other relatives, such as Homo heidelbergensis.

Relatives of cats, hyenas, would have also posed a threat to our ancestors, especially the hunting hyena, Chasmoporthetes. 

Chasmaporthetes and Other Hyenas

Chasmaporthetes was a diverse genus of extinct hyena, which lived from 4.9 million years to 780,000 years ago, living throughout Afro Eurasia and into North America as well. The most well known species was Chasmaporthetes ossifragus, which lived in North America. It was a very fast and powerful hunter, preying upon other mammals like llamas, camels, deer, peccaries, and other small mammals. The species Chasmaporthetes lunensis ruled in Afro Eurasia. Chasmaporthetes often hunted human ancestors as well, including Homo erectus in Asia. 

Hyenas are very prominent carnivores in Africa, but are mainly scavengers. It is possible that hyenas scavenged the hominin remains in the caves in South Africa. These hyenas would have been brown hyenas (Parahyaena brunnea) however, a living species, not the extinct Chasmaporthetes. 

Outside of Africa, humans coexisted with other hyena species, such as the 46-33,000 year old Manot cave in Israel. The hyenas here were spotted hyenas (Crocuta crocuta). Bone assemblages from this cave show that the hyenas were mostly feasting upon fallow deer and mountain gazelles. 

The humans here were also hunting other gazelles, but of different group sizes. The humans may have been hunting in more open areas due to their use of projectile weapons, but this also may be an example of niche partitioning amongst. humans and hyenas. Neanderthals in France were living alongside cave hyenas, exploiting different animal resources, just like the modern humans in Israel. The interactions between humans and hyenas in Europe weren’t always peaceful however. 

In Guattari Cave, Italy, 9 Neanderthal individuals were uncovered. These Neanderthals weren’t living in this cave however, rather they were brought into it by hyenas. Many remains of Hyenas and Neanderthals are known from this cave, dating from 90-50,000 years ago. These hyenas were scavenging the bones of mostly adult males, along with one adult female and one juvenile. Along with Neanderthals, these hyenas were also scavenging on cows, rhinos, deer, bears, elephants, and horses.

Drimolen cave, South Africa, which dated to 2-1.5 million years ago, possesses remains of Dinofelis, modern leopards, and Chamaporthetes, showing that these African predators lived nearby to one another. There would have been some competition between these predators, especially the big cats that hunted in the South African environments, which were hunting the hominins in the area, along with baboon species. Chasmoporthetes had a more varied diet however.

Felids and hyenas were the most common predators in South Africa, with hyenas most commonly scavenging the hominins, just like what they do today. This was similar in eastern Africa, with felids being the primary predators.They would be hunting species like Paranthropus boisei and Australopithecus afarensis.

It is very clear that our ancient ancestors faced many dangers during their time from other animals. This begs the question, how did this affect our evolution? What evolutionary pressures did our predators produce? There are several ways these questions could be answered. 

How Our Predators Shaped Us

There are multiple aspects of human biology and behavior that are results of our ancient predators. One big thing is our social structures. 

Just like how other primates live in large social groups to avoid predators, it seems our ancestors did the same. The behaviors of other hominins are best compared to modern baboons as they live in similar environments. Primates that live in more open environments tend to have larger social groups as a predator avoidance tactic. Hominins more closely related to modern humans, like Homo ergaster, also lived in very sizable groups, having big implications for modern human sociality. 

Comparisons with modern primates, mainly chimpanzees and baboons, suggests that Homo ergaster lived in large groups with many males, who would defend the group from predators. Defending against predators could have also developed into cooperative hunting, something very important for modern human behavior. 

One of the reasons humans (and other primates as well) are so social and form such tight social groups could have started out as responses to the predation we faced in the African savanna. This is a human behavior shaped by predation, but there are also physical changes as well. 

Primates have incredible vision compared to other mammals, including humans, at the cost of other senses, such as smell. One reason for this may be the dangers we faced in our past, mainly, snakes, big threats to not just primates, but all animals.

Snake bites are difficult to discern from fossils, but it is very likely that our ancestors faced them. Many dangerous snakes live in Africa, such as cobras, black mambas, vipers, and pythons, all of which pose threats to animals in Africa today, and no doubt would have done the same for our ancestors. 

Snakes and placental mammals have evolved side by side, and snakes likely were one of the first major predators of these animals. Primate groups that have been more exposed to venomous snakes have larger parts of the brain associated with fear. 

Snakes and primates have very interesting relationships. Many species of primates have been observed approaching, mobbing, killing, and even eating snakes. 26 primate species, including species which have attacked snakes, have been observed being killed and eaten by snakes. There is often aggression from both sides. 

Similarly, studies on the Agta Negritos from the Philippines, have shown that these peoples have hunted and eaten pythons, along with deer, pigs, and wild monkeys. These same peoples have also been hunted by the same pythons. 26% of adult males have been reported to have survived python attacks, and 6 deaths were reported between 1934-1973. Though not super common, predation from snakes on primates is prevalent enough to have a possible evolutionary significance. 

Humans and other primates are very sensitive to images of snakes, more so than any other animal. Having increased vision would have been very beneficial for detecting the camouflaged snakes. Mosaic snakes, equivalent to camouflage snakes, stand out to people much more than any other animal. Snakes have even appeared as more threatening than guns and knives, things that are much more dangerous in the present day. 

This suggests that humans have an instinctual fear response to snakes, as a result of visual adaptations to avoid snakes. This idea is known as snake detection theory. This theory is further backed up by the fact that other primates have similar responses to snake images.

Vervet and macaque monkeys respond very strongly to partially exposed images of snakes and images of snake scales more than any other animal, mainly lizards and birds. A natural fear response towards snakes is not only present in humans, but many primates, showing that it’s an ancestral instinct, seemingly from the earliest primates which evolved alongside snakes.

The predation from these threatening reptiles shaped our brains and senses, having effects in our brains even to this day. 

Conclusion 

Though today, we are mostly safe from the predators that hunt the animals that live alongside us, this hasn’t always been the case. Evidence of predation on humans and our ancestors is found from as recent as 3,000 years ago to as long ago as 3 million years ago. From water bound sharks, to land ridden big cats, and to airborne eagles, our ancestors have always been in danger. These predators have had big effects on our evolution as well, altering our sociality, and even possibly our vision. As sad as it is to think about these ancient apes being hunted, we should also be grateful for it, as without these past dangers, we wouldn’t be the way we are today. 

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