Explorations Chapter 8 Primate Evolution

Summary

This lecture delves into primate evolution, exploring hypotheses like arboreal adaptation, visual predation, and angiosperm-primate co-evolution. It traces primate origins post-dinosaur extinction, highlighting the rapid diversification of mammals, known as adaptive radiation. The instructor discusses various primate groups' geographical distribution, evolutionary relationships, and the significance of the fossil record in understanding their history. The talk concludes with a focus on human evolution, emphasizing the close genetic ties between humans and chimpanzees.

Takeaways

• 🌳 The arboreal hypothesis suggests that primates evolved adaptations for living in forests, such as grasping fingers and 3D vision for navigating trees.
• 🐛 The visual predation hypothesis proposes that primates evolved traits like 3D and color vision to hunt insects effectively.
• 🍎 The angiosperm-primate coevolution hypothesis states that early primates evolved to consume fruit, which may explain the development of color vision.
• 🦕 Primates originated after the extinction of dinosaurs, during a time when mammals rapidly evolved to fill ecological niches left vacant, a process known as adaptive radiation.
• 🕊️ Mammals, including early primates, existed during the Mesozoic era alongside dinosaurs but were small and not widespread until the dinosaurs' extinction.
• 🌏 The breakup of the supercontinent Pangaea led to the separation of primate populations and subsequent evolution in isolation, contributing to the diversity of primates.
• 📜 Fossil evidence is crucial for understanding primate evolution and migration, but gaps in the fossil record can make it challenging to trace exact relationships.
• 🌴 Modern primates are distributed across different continents, with New World monkeys in Central and South America, prosimians like lemurs in Madagascar, and apes in Asia and Africa.
• 🔍 The adapoids and omomyoids are extinct primate groups that are considered the ancestors of modern lemurs, lorises, and tarsiers, with various debates on their exact evolutionary relationships.
• 🌊 Platyrrhines, the New World monkeys, likely migrated from Africa to South America, possibly via a land bridge or floating vegetation rafts during periods when the continents were closer.
• 🌾 The evolution of catarrhini, including Old World monkeys and apes, is traced back to common ancestors, with significant divergences and speciation events over millions of years.

Q & A

What is the main topic of Chapter eight in the physical anthropology course?

The main topic of Chapter eight is primate evolution, covering various hypotheses about why it occurred and the evolutionary history of primates.

What are the three hypotheses discussed in the script regarding the evolution of primates?

The three hypotheses are the arboreal hypothesis, the visual predation hypothesis, and the angiosperm-primate coevolution hypothesis.

What does the arboreal hypothesis suggest about the evolution of primates?

The arboreal hypothesis suggests that primates evolved adaptations for living in forest habitats, such as grasping fingers and 3D vision, because the majority of primates live in forests.

How does the visual predation hypothesis explain the evolution of primate traits?

The visual predation hypothesis posits that traits like 3D vision and color vision evolved in primates to help them hunt insects more effectively.

What is the angiosperm-primate coevolution hypothesis and what does it suggest about primate diet?

The angiosperm-primate coevolution hypothesis suggests that early primates evolved to eat fruit, which could explain the evolution of color vision and other traits related to arboreal living.

What was the Mesozoic era known for, and how did it relate to primate evolution?

The Mesozoic era was known as the age of dinosaurs, which were the dominant land organisms. Mammals, including early primate ancestors, were small and lived in trees. After the extinction of dinosaurs, mammals, including primates, rapidly evolved to fill the ecological niches left vacant.

What is adaptive radiation, and how does it relate to the evolution of mammals after the extinction of dinosaurs?

Adaptive radiation is a process where an ancestral species rapidly diversifies into many new forms to occupy various ecological niches. After the extinction of dinosaurs, mammals underwent adaptive radiation, leading to the emergence of the first primates.

What is the significance of the fossil evidence in understanding primate migration and evolution?

Fossil evidence provides insights into the geographical distribution of primates in the past and helps scientists hypothesize about migration patterns and evolutionary relationships among different primate groups.

How did the breakup of the supercontinent Pangaea affect primate evolution?

The breakup of Pangaea led to the separation of continents, which in turn resulted in less interbreeding among primate populations. This isolation allowed for more independent evolution as populations adapted to their unique environments.

What are the four hypotheses proposed for the migration of platyrrhines to South America?

The four hypotheses are: 1) migration from North America through Central America, 2) direct migration from Africa across the Atlantic Ocean possibly using vegetation rafts, 3) migration via Antarctica when it was at a different latitude and climate, and 4) independent origin within South America.

How are the terms 'lesser apes' and 'great apes' used in the context of primate evolution, and what are some examples?

Lesser apes refer to gibbons and siamangs, while great apes include chimpanzees, gorillas, orangutans, and humans. These terms distinguish between different branches of the ape family tree based on evolutionary relationships and characteristics.

What is the significance of the Sivapithecus in the study of ape evolution, and where was it found?

Sivapithecus is an extinct ape ancestor that was found in Asia and is believed to be the ancestor of orangutans, providing important information about the evolutionary history and geographical distribution of apes.

What was Gigantopithecus, and how does its size compare to modern great apes?

Gigantopithecus was probably the largest ape that ever existed, standing over 10 feet tall and weighing an estimated 1000 pounds. It was much larger than modern great apes like gorillas.

Outlines

00:00

🌳 Primate Evolution and Arboreal Hypothesis

In this segment, Annabella Kraut introduces the topic of primate evolution, focusing on the arboreal hypothesis which suggests that primates evolved to adapt to forest habitats. Evidence supporting this hypothesis includes the predominance of primates in tropical forests and their adaptations for arboreal life, such as grasping fingers and 3D vision. The lecture also briefly touches on alternative hypotheses for primate evolution and sets the stage for a deeper dive into primate evolutionary history.

05:17

🔍 Exploring Hypotheses and Primate Migration

This paragraph delves into various hypotheses for primate evolution, including the visual predation hypothesis, which posits that primates evolved specific traits for hunting insects, and the angiosperm-primate co-evolution hypothesis, suggesting that early primates evolved to consume fruit. The summary also covers the evolutionary history of mammals post-dinosaur extinction, highlighting the rapid diversification of mammals, known as adaptive radiation, and the rise of the first primates around 65 million years ago. Additionally, it discusses the distribution of modern primates and the implications of continental drift on primate evolution.

10:26

🦍 Early Primate Ancestors and Adaptive Radiation

Annabella Kraut discusses the fossil evidence of early primates, including adapoids and omomyoids, and their distribution during the Eocene epoch. The paragraph explores the concept of adaptive radiation, where a single organism rapidly evolves into many different forms to fill various ecological niches. It also examines the migration of primates, suggesting possible routes from Asia to Europe and North America, and the potential for early primates to cross bodies of water or travel via land bridges. The summary emphasizes the uncertainty in pinpointing exact evolutionary relationships due to gaps in the fossil record.

15:34

🌏 Platyrrhine Origins and Catarrhine Evolution

The final paragraph examines the origins of platyrrhines, or New World monkeys, and the hypotheses surrounding their migration to South America, including potential routes via Antarctica or direct ocean crossings. It then shifts focus to catarrhines, discussing early fossils like Aegyptopithecus and tracing the evolutionary lineage of monkeys and apes, highlighting the divergence of gibbons, orangutans, gorillas, and humans. The summary underscores the close genetic relationship between chimpanzees and humans, sharing approximately 98% of DNA, and mentions the extinct Sivapithecus and Gigantopithecus, providing a comprehensive overview of primate evolution and diversification.

Keywords

💡Arboreal Hypothesis

The arboreal hypothesis is a theory suggesting that primates evolved certain physical traits due to their adaptation to a forest habitat. It is central to understanding primate evolution as it explains why many primates have grasping hands and feet, which are essential for life in the trees. In the script, this hypothesis is supported by the fact that most primates live in tropical forests and possess adaptations for arboreal life, such as 3D vision for judging distances while leaping between branches.

💡Visual Predation Hypothesis

The visual predation hypothesis posits that certain primate traits, like 3D and color vision, evolved as adaptations for hunting insects. This concept is integral to the discussion on primate evolution as it offers an alternative explanation for the development of advanced visual capabilities in primates. The script mentions this hypothesis in the context of explaining the evolution of primate vision as a specialized adaptation for insect predation.

💡Angiosperm-Primate Coevolution Hypothesis

This hypothesis proposes that early primates evolved to consume fruit, leading to a mutualistic relationship with flowering plants (angiosperms). It is relevant to the video's theme as it provides a scenario for the evolution of color vision and other traits that aid in fruit consumption. The script illustrates this by pointing out the color contrast between unripe and ripe fruit, which could have driven the evolution of primate color vision.

💡Mesozoic Era

The Mesozoic Era, often known as the 'Age of Dinosaurs,' is a significant geological time period mentioned in the script that sets the stage for understanding primate origins. During this era, dinosaurs dominated the land, but small mammal-like creatures, which would eventually give rise to mammals and primates, also existed. The script uses the Mesozoic Era to highlight the time when mammals, and subsequently primates, began to evolve.

💡Adaptive Radiation

Adaptive radiation refers to the rapid evolution of a single ancestral species into several diverse forms to exploit different ecological niches. In the script, this concept is used to describe how mammals, including early primates, rapidly diversified after the extinction of dinosaurs, filling the vacant niches and leading to the emergence of various primate groups.

💡Adapoids

Adapoids are an extinct group of primates considered to be the ancestors of lemurs and lorises. They are significant in the script's discussion of primate evolution as they represent an early branch of primates that were diurnal and herbivorous. The script mentions adapoids in the context of early primate evolution and their contribution to the diversity of modern primates.

💡Omomyoids

Omomyoids are another extinct group of early primates, believed to be the ancestors of tarsiers. They are nocturnal, insectivorous, and frugivorous, and their study helps in understanding the evolutionary history of primates. The script discusses omomyoids in relation to the early diversification of primates and their ecological roles.

💡Platyrrhines

Platyrrhines, or New World monkeys, are a group of primates native to South and Central America. The script explores various hypotheses about their origins and migration to South America, making them a key concept in understanding the geographic distribution and evolution of primates.

💡Catarrhini

Catarrhini, including Old World monkeys, apes, and humans, are a group of primates characterized by their reduced snout and downward-facing nostrils. The script discusses the evolution and diversification of catarrhini, highlighting their significance in the primate family tree and their evolutionary journey from early ancestors to modern species.

💡Gigantopithecus

Gigantopithecus is an extinct ape species mentioned in the script, notable for being one of the largest apes that ever lived, surpassing the size of modern gorillas. Its mention serves to illustrate the diversity and adaptability of ape ancestors, and it provides an interesting example of primate evolution and extinction.

💡Continental Drift

Continental drift is the geological process by which continents move across the Earth's surface over time. In the script, it is discussed in the context of how the separation of landmasses affected primate evolution by limiting gene flow between populations and promoting speciation. This concept is crucial for understanding the distribution of primate species across different continents.

Highlights

Introduction to primate evolution in Chapter eight of the physical anthropology course.

Discussion of hypotheses about primate evolution and their supporting evidence.

Arboreal hypothesis suggests primates evolved adaptations for forest habitats.

Visual predation hypothesis proposes 3D and color vision for insect hunting.

Angiosperm-primate coalition hypothesis links fruit eating to primate evolution.

Review of the Mesozoic era and its significance for mammal and primate evolution.

Explanation of adaptive radiation following the dinosaur extinction event.

Identification of primate origins post-dinosaur extinction around 65 million years ago.

Review questions on primate evolution hypotheses and their key traits.

Geographical distribution of modern primates and their evolutionary migration.

The role of continental drift in primate evolution and speciation.

Fossil evidence of early primates like adapoids and omomyoids during the Eocene epoch.

Hypotheses on the migration and evolution of platyrrhines in South America.

Evolutionary timeline of catarrhini, including the divergence of Old World monkeys and apes.

The last common ancestor of chimpanzees and humans around 9 million years ago.

Mention of Sivapithecus as an extinct ape ancestor found in Asia, possibly related to orangutans.

Gigantopithecus, the largest ape that ever existed, and its significance in primate history.

The dynamic nature of scientific hypotheses and their evolution with new evidence.

Transcripts

Annabella Kraut: Welcome to physical anthropology in Chapter eight we're going to be taking a look at primate evolution.

Annabella Kraut: The topics for today include looking at the various hypotheses about primate evolution and why it occurred and then looking at the evolutionary history of primates, including the rise of mammals, the adapoids and omomyoids, the platyrrhine evolution and the catarrhine evolution.

Annabella Kraut: So why did primates evolve, where did they come from, what's going on with that, we actually have three different possible hypotheses and all of them have different types of evidence supporting them.

Annabella Kraut: So the first hypothesis is the arboreal hypothesis, arboreal has to do with forests and trees, so this hypothesis explains that the reason primates look the way they do is because they evolved to be adapted to a forest habitat.

Annabella Kraut: And there is evidence to support this, for example, the vast majority of primates that are alive today do live in the forest, specifically tropical forest, regardless of which continent, they live on.

Annabella Kraut: Many of them still live in the trees, though some of them have evolved to now live on the ground instead.

Annabella Kraut: And many of them have these adaptations that are excellent for living in trees, such as the grasping fingers, the ability to see in 3D so they can judge distances when they're jumping from tree branch to tree branch, and also the ability to.

Annabella Kraut: to eat the objects in the trees, whether it's the fruit, the leaves or the insects.

Annabella Kraut: The next hypothesis it's a little bit more specific, it's the visual predation hypothesis, and this hypothesis.

Annabella Kraut: The reason we have these traits, such as the 3D vision and color vision is because we evolved to hunt insects, so this is just an alternative way of explaining why those traits are in primates.

Annabella Kraut: Finally, the angiosperm-primate coalition hypothesis says that our early primary ancestors actually evolved to eat fruit.

Annabella Kraut: one kind of interesting idea for that one is that if you look at fruit, a lot of times the unripe fruit is still green or yellow.

Annabella Kraut: While the ripe fruit is a brighter color like red, so this could explain why color vision evolved, as well as some of those other traits which would be about living in the trees.

Annabella Kraut: Now this picture, hopefully looks familiar to you, it is that history of life on Earth all the different eras, and what we're going to look at.

Annabella Kraut: is specifically primate origins, so primate origins are going to happen after the extinction of the dinosaurs so let's kind of review a little bit here.

Annabella Kraut: The mesozoic time period.

Annabella Kraut: The mesozoic time period was also referred to as the age of the dinosaurs and that's because for many.

Annabella Kraut: Hundreds of millions of years during that triassic, jurassic, and cretaceous period the dinosaurs were the dominant organisms on land.

Annabella Kraut: However, mammals did exist at this time period so mammals did evolve about 200 million years ago, but they were these small little, almost rat-like or shrew-like creatures that lived in the trees in the forest and they were not that.

Annabella Kraut: Not that widespread.

Annabella Kraut: So what happened at the end of the cretaceous is that unfortunately that was this mass extinction for dinosaurs, but the mass extinction for the dinosaurs was an amazing opportunity for mammals.

Annabella Kraut: And what happened is that the mammals evolved very rapidly to take over all of the empty niches that the dinosaurs left behind.

Annabella Kraut: Now, do you remember the name of that kind of evolution when you start with an organism, which is one type of organism, one type of body shape, and it evolves rapidly to all of these many different types of organisms.

Annabella Kraut: So some of them might now live in the trees, still others might now live on the ground, others might move into the water, others might move into the air and be able to fly, so why is all this rapid evolution occurring.

Annabella Kraut: there's a name for that we call it adaptive radiation, so now all these mammals exist, you see the first primates almost immediately after the extinction of the dinosaurs 65 million years ago.

Annabella Kraut: So here's my first review question for you.

Annabella Kraut: The arboreal hypothesis of primate origins emphasizes that primates A) have grasping hands and feet B) have a fruit eating tendency C) long legs compared to arms or D) acute sense of smell.

Annabella Kraut: So, remember that for arboreal it had to do with being in the trees and to be able to grasp the branches of the trees, you need A.

Annabella Kraut: next question for you the visual predation hypothesis argues that the unique traits of primates evolved in order to hunt what A) reptiles B) birds C) insects or D) mice.

Annabella Kraut: In the case of this early primate we think it evolved to potentially eat insects.

Annabella Kraut: Finally, the angiosperms primate co evolution hypothesis notes that the earliest primates likely ate what.

Annabella Kraut: So angiosperms refers to a type of plant that has flowers, and the reason it has flowers is because it's used to attract pollinators to produce fruit, so what we think they ate was fruit.

Annabella Kraut: In this image what i'm going to show you is where modern primates can be found.

Annabella Kraut: So we have the new world monkeys which we've discussed before these guys are only found in the tropical areas of South and Central America.

Annabella Kraut: Next, we have the prosimians which, of course, is not a correct grouping in terms of evolution, but the lemurs are only found here on Madagascar, the island of Madagascar, while things like lorises and tarsiers.

Annabella Kraut: Well, lorises are found in both central Africa as well as some islands over here in Asia, tarsiers to only found here in the Philippines.

Annabella Kraut: Then we have the old world monkeys, old world monkeys are going to be found in Africa as well as throughout the Middle East and southern Asia.

Annabella Kraut: And then apes, so for apes things like gibbons and orangutans are found over here in Southeast Asia, while chimpanzees, bonobos and gorillas are only found in Central Africa.

Annabella Kraut: So that's where the primates are now, but where did they come from, or how did they migrate, where did they go, what's going on with that, it has to do with the fossil evidence that we can find.

Annabella Kraut: And one thing to kind of keep in mind is the image on the bottom right, the idea that we did used to have this massive continent called pangea.

Annabella Kraut: And that pangea started to break up about 200 million years ago, or so and the continents started to drift apart, so once the continents drifted apart.

Annabella Kraut: there's going to be less interbreeding across groups, right, and so there's going to be more evolution, the more distantly.

Annabella Kraut: These primates are separated from each other, because they're going to continue to evolve in their own unique environment but there's not going to be any gene flow amongst those populations.

Annabella Kraut: This next map is showing you that during the eocene epoch we're going to have fossils of the adapoid

Annabella Kraut: And the omomyoid in these areas, we actually do see it in North America and Africa, and what will eventually become Europe as well as in Asia, So what is this eocene in time period.

Annabella Kraut: it's right here it's right around between 34 million years ago, all the way back to 55 million years ago.

Annabella Kraut: Now, how did the primates get from one continent to another, in some cases, the islands may have been close enough that they could actually you know.

Annabella Kraut: walk across depending on the environment, it's also possible that they could cross bodies of water, if there were something else that was floating across.

Annabella Kraut: So in this picture on the right we're talking about how this particular early primate, which kind of looks like a vertical clinger leaper, may have started off here in Asia and then migrated across to the European continent and then over to North America.

Annabella Kraut: Then in the bottom picture we have what's happening in the miocene, these are specifically apes, so now that's a subcategory of primates right and we know that modern day apes, mostly live here in Africa, some of them still have here in Asia.

Annabella Kraut: But the ones that used to live in in Europe, all of these guys have gone extinct.

Annabella Kraut: The miocene time period would have been after the eocene, so it would have been right here.

Annabella Kraut: About five to 16 million years ago.

Annabella Kraut: So we did have some evidence of archaic primates that existed, right after the the extinction of the dinosaurs 65 million years ago.

Annabella Kraut: But what we're going to focus on are the euprimates, are the true primates, So these are going to be the direct ancestors of some of our modern primate groups.

Annabella Kraut: Including the adapoids which are going to be the ancestors of lemurs and lorises as well as the omomyoids, which are the ancestors of tarsiers.

Annabella Kraut: So let's compare these two groups to each other, the adapoids are these ancestral animals that were diurnal, you hopefully recall that that means they are active during the day.

Annabella Kraut: They were herbivorous so they're eating plant material and they were relatively large, now we know that some lemurs are still diurnal but some of these other animals, like the lorises.

Annabella Kraut: have actually become nocturnal, then for the omomyoid, we have nocturnal insectivorous frugivorous and relatively small but interestingly, the tarsiers are no longer frugivorous, they're eating small animals now.

Annabella Kraut: you've seen this image before, this is the cladogram that shows the evolutionary relationships of all of our modern living primates So what we can do for this tree right now is add.

Annabella Kraut: The adadpoids and the omomyoids here, because the adadpoids would have basically been at the beginning of the group of strepsirrhini.

Annabella Kraut: While the omomyoids it's not quite clear where exactly they belong, we know that they're the ancestors of the tarsiers, but how are they related to these other two groups, the platyrrhini and the catarrhini that.

Annabella Kraut: is still up to debate and I'm going to show you a couple different hypotheses on how they might be related.

Annabella Kraut: So this is a more detailed cladogram that now shows, not just the living organisms, So these are all of our living primates here at the tips of the branches, but it also shows some examples of.

Annabella Kraut: animals that have gone extinct, so like these guys here they've gone extinct, the adapoids are, of course, the ancestors, there's many branches here that have gone extinct, here's the omomyoids and what we see is that right here.

Annabella Kraut: Is kind of big question mark.

Annabella Kraut: So we're not sure whether a branch split off long before the omomyoids came into existence and that that branch then became the ancestors of apes and monkeys, or did it happen after the omomyoids.

Annabella Kraut: evolved and on the right hand, I have a couple different possible hypotheses of what could happen, so in this example the anthropoids and the adapoids actually have the most common recent ancestor so that's in complete opposite to what we see on the picture on the left.

Annabella Kraut: In the second cladogram the anthropoids are related to the tarsiers, but their common ancestor is longer ago than the omomyoids, so that's most similar to what we have in this picture on the left.

Annabella Kraut: And then the bottom one says that anthropoids and the tarsiers are actually like a cousin species, they have a common ancestor but the omomyoids.

Annabella Kraut: existed even before that, so it's just an alternative way, it's really hard to sometimes figure out these evolutionary relationships, because we have missing links in the fossil record.

Annabella Kraut: And what you're going to see is that while fossils do exist, sometimes there can be hundreds of thousands of years or even millions of years in gaps between the samples that we find so we found.

Annabella Kraut: An animal that exists here, and then we find an animal that exists here, we have to hypothesize on what happened in between we're not quite sure until we find.

Annabella Kraut: Another fossil that fits in there, and then that's usually a "missing link" and we'll talk about missing links more when we get to human evolution.

Annabella Kraut: Because, for a long time, there were missing links and new fossil evidence helped shape our hypotheses, of how human evolution has occurred so don't forget science is an evolving process and as new evidence comes into being, we use that to change our hypotheses and update them.

Annabella Kraut: So the next picture is going to look at the platyrrhines so what happened with them like where did they come from.

Annabella Kraut: Because we know that there's no direct ancestors of them existing in South America, so the question is how did they get to South America.

Annabella Kraut: And there's four different possible hypotheses in this image, so in image number one.

Annabella Kraut: What we think is that the existing monkeys that did live in North America or the ancestors of these monkeys.

Annabella Kraut: That they just migrated down to South America, using Central America as their path, and then the South American monkeys continue to exist, while the North American monkeys went extinct.

Annabella Kraut: So that's one possibility, a second possibility is that they came from Africa directly to South America, so they had to cross the water, cross the Ocean to get there.

Annabella Kraut: The third hypothesis is that they did get to South America, but not across the Atlantic instead through.

Annabella Kraut: A smaller gap to Antarctica and then to South America, now, you might wonder like why on earth would they go to Antarctica.

Annabella Kraut: Remember that when this is happening with continental drift Antarctica wasn't necessarily as freezing cold, as it is now so because the continent would have been.

Annabella Kraut: You know, a different latitude, it might have still been pleasant enough for this migration to be possible.

Annabella Kraut: And then the fourth hypothesis here is that they simply originated independently there's just not as much evidence of that.

Annabella Kraut: So the most plausible scenario we think is going to be this scenario, right here and number two, which is that they did originate in Africa.

Annabella Kraut: And then, what happened is they crossed over to South America, possibly when those two continents were still.

Annabella Kraut: close enough for this to be able to happen, they didn't swim or anything like that, instead, they may have gotten trapped on to these.

Annabella Kraut: vegetation rafts, which are you know, like large debris of fallen trees and other things like that, and they would just kind of float along with the wind until they reach South America.

Annabella Kraut: Now, of course, some animals would get lost at sea, but as long as a few of them, made it to South America, then they could now.

Annabella Kraut: Take over any part of the ecosystem there that has an empty niche, and so the monkeys in South America actually quite successful, and they would have continued to evolve separately from their relatives in Africa.

Annabella Kraut: We know of course that the South American monkeys do have some unique traits that are only found there, like that prehensile tail.

Annabella Kraut: So now let's look at the catarrhini and what's going on with them.

Annabella Kraut: So one of the earliest fossils that we find is something called the Aegyptopithecus and this organism was relatively large for a monkey.

Annabella Kraut: And it was an arboreal quadruped meaning, it is running around in the trees, using all four limbs.

Annabella Kraut: there's clear sexual dimorphism, because in the fossil in this image, the right organism is the male and the left organism is a female, the same species, so the males clearly larger, it has larger canines a much more robust skull.

Annabella Kraut: Now this ancestor went extinct, but we think that there's another common ancestor between the monkeys and the apes about 25 million years ago, so down here, these are going to be all of our old world monkeys.

Annabella Kraut: While up here, we have all of these apes and they diverged about 25 million years ago, following this graph.

Annabella Kraut: let's continue about 18 million years ago would have been the last common ancestor between the lesser apes, so the lesser apes are the gibbons and the siamangs, versus the great apes, which include the chimps gorillas and orangutans.

Annabella Kraut: About 14 million years ago would have been the evolution of the orangutans in their own branch, then about 12 million years ago was our common ancestor with gorillas.

Annabella Kraut: And finally, about 9 million years ago would have been the last common ancestor between the chimpanzees and the humans, we do know that the chimpanzees and the humans are of course the most.

Annabella Kraut: related of the existing living primates and we share, about 98% of our DNA, so it took 9 million years just for those 2% differences to evolve.

Annabella Kraut: And then, this branch right here the human branch is going to be where we're going to continue the conversation in the future on human evolution so that's now going to be all the hominins all of those.

Annabella Kraut: ancestors, who do walk up right, but unfortunately they've gone extinct.

Annabella Kraut: One other organism I'm going to mention on this graph is something called the Sivapithecus, and so the Sivapithecus is an extinct ape ancestor.

Annabella Kraut: But the reason it's kind of interesting is because it was found in Asia, and we think it is the ancestor of the orangutans, so it is right here on the graph it would have been its own branch, related to the orangutans.

Annabella Kraut: There are of course many other extinct apes and your textbook does go into a lot of detail on that so you're welcome to learn more about these other interesting animals.

Annabella Kraut: But one of the most interesting, in my opinion it's something called the gigantopithecus.

Annabella Kraut: Which is a great name, because it was gigantic, it is probably the largest ape that has ever existed, so if you thought gorillas were big, this one way surpasses it.

Annabella Kraut: And in this graph you can see an image of one of the largest specimens compared to human it was over 10 feet tall, and we estimate, based on the skeletal remains.

Annabella Kraut: That it could have been about 1000 pounds so huge if you've ever heard of bigfoot.

Annabella Kraut: Maybe that's where this myth comes from, maybe somebody found these ape bones and thought that it was, you know bigfoot but, in any case, unfortunately this guy did go extinct.

Annabella Kraut: But he was really, really big and he actually just ate plants, so he was kind of like a gentle giant, he wasn't a hunter, but when the environment changed he went extinct.

Annabella Kraut: And that wraps it up for Chapter eight.