Primates and Homonids - Online Tutor, Practice Problems & Exam Prep

Primates, including humans and chimpanzees, are characterized by large brains, complex visual systems, and social behaviors. They possess features like opposable thumbs, which aid in tool use. Primates are divided into prosimians (e.g., lemurs) and anthropoids (e.g., monkeys, apes). Hominids, a subgroup of anthropoids, include species like Australopithecus and Homo, with Homo sapiens being modern humans. Key evolutionary traits include bipedalism, which allows walking on two feet, and the significant genetic similarity between Neanderthals and modern humans, highlighting our shared ancestry.

Primates

In this video, we're going to briefly discuss primates, which includes organisms such as ourselves and some of our more closely-related organisms such as chimpanzees. And so, primates are really just a group of mammals that are characterized by very specific features such as large brains and sophisticated visual systems. And, in fact, in the back of our heads, there's a region of our brain called the occipital lobe which controls our complex visual systems. Now, primates are also characterized by features such as having good parental care, meaning that they take good care of their offspring, and they are also characterized by having complex social behaviors. Now, some primates have opposable thumbs, which is really just a non-digit finger such as our thumb that is going to allow for grasping in the utilization of tools as well as fine motor skills, and so a fully opposable thumb is one in which the thumb is able to touch the front of the fingertips for each of the 4 digits. And so, humans have fully opposable thumbs but so do gorillas, and chimpanzees also have opposable thumbs as well. Now, what you'll notice is that the gibbon, it does have this thumb as you see here, however, it is distant from the fingertips, is pretty great in comparison to the chimpanzee, gorilla, and human. And again, the human isn't mentioned. And so what you'll notice is that because there's such a great distance here, they do not have fully opposable thumbs that allow them to touch their thumb to the front of their fingertips. And what you'll notice is the tarsier over here is also going to have more primitive-like features where it is not going to have a fully opposable thumb. Now, in general, these primates can be broken up into 2 major groups and those 2 major groups are the prosimians and the anthropoids or the simians. Now the root "pro" in prosimian is a root that means before, and so prosimians are going to be a group of primates that are more similar to early primates, and that's where the pro comes into play. Again pro means before, so you can think early or you know earlier primates. And the prosimians include lemurs and lorises and also the tarsiers. And so notice down below we're showing you this image of a lemur, which again is a prosimian and it is going to have features that are more similar to early primates. Now the other major group of the primates are the anthropoids or the simians and these are going to be bigger-brained primates that are going to include monkeys and apes and humans and chimpanzees and so notice down below we're showing you this image of these chimpanzees that are showing these complex social behaviors and so those are going to be an example of the anthropoids or the simians. Now these anthropoids or simians can be further grouped into what are known as hominids. And so, hominids can be defined as these are anthropoids, and the hominids are also sometimes called great apes. And so the hominids include gorillas, chimpanzees, bonobos, humans, and orangutans. And so if we take a look at this image down below what you'll notice is we're showing you the skeletal structure of these different primates. And we can use this image to introduce this term bipedalism. And so the term bipedalism refers to the ability to walk only on the two hind limbs, and so basically it's saying the ability to walk on 2 feet. That is what bipedalism is. So, humans are fully bipedal as adults, and what you'll notice is that many of the great apes are actually not fully bipedal and so the great apes here are going to include humans, but humans are the only ones that are fully bipedal. They're the only ones that can walk on 2 feet predominantly. Now the chimpanzees, gorillas, and orangutans, they are great apes. However, what you'll notice is that they can use their hands and they tend to use their hands for a lot of the motions and movement. And a lot of their arms, you can see the bone structure for their arms, are much longer and very extended and their posture is bent so that they can more conveniently use their hands in addition to their feet to move around. Now the gibbon on the other hand over here is not actually a great ape, it is an anthropoid but it is not a hominid and so the gibbon here also has the long extended skeletal structure in its arms and so the gibbon is going to walk more using all 4 of its limbs. So it is not going to display that bipedalism. And so this here concludes our brief introduction to some of the features of primates and some of the groups of these primates, and I'll see you all in our next video.

Homonids

Australopithecus is a genus of hominids that lived from about 4,000,000 years ago to about 2,000,000 years ago. The organisms in this genus played an important role in human evolution. Over here, you can see the reconstruction of a skull of an Australopithecus species, Australopithecus afarensis, which you can see that name printed on this map over here. And so that is the species name, and next to that skull, we have a reconstruction of that organism, what people think it might have looked like. This is based on partial fossils that have been uncovered. So, there's some artistic license being taken here. But this is thought to be the ancestor, or an ancestor of modern humans, Australopithecus afarensis, and this particular organism is known commonly as Lucy, which is the common name given to a particular skeleton of the species that was found. As you can see in this map, there are many different species of Australopithecus, and they're found all over Africa. Australopithecus is indeed native to Africa, and there were a bunch of different species in that genus. Now, from that genus arises this new genus, Homo. That's the genus that we belong to. It's thought that the lineage of hominids evolved from possibly Australopithecus afarensis around 2,000,000 years ago. So, let's actually take a look at some of the species in the genus Homo. Now, an early species in the genus Homo is Homo habilis, and that, I'm abbreviating the name here just to be clear. So habilis is short for Homo habilis. And, basically this, this name just means handyman, and these organisms were named for their tool use. They're very early humans, and some scientists actually believe that they're better classified in the Australopithecus genus, rather than the genus Homo. So, that line, that distinction is not super clear-cut. Right? It's not super explicit. There's a vague enough transition that some people even classify Homo habilis as Australopithecus habilis, for example. Another early species is Homo erectus, and also Homo ergaster. These early humans originated in Africa but actually emigrated from the continent. And here in this map behind my head, you can see the path taken by early humans. And we're actually looking at three different species, and in yellow is the distribution of Homo erectus. So you can see they were found in Africa, but they also crossed over, via the Sinai Peninsula, to the Arabian Peninsula. And they also made it into the Indian subcontinent, Southeast Asia. However, it was Homo neanderthalensis that made it up into Europe. Right? So those guys are colored in orange. And you can see that they were found, really, like, all across Europe, into the Bactrian region, all around the Black and Caspian Seas, and even on the island of Albion, or as we know it today, England. Now, these guys, these Homo neanderthalensis, these are what we often commonly refer to as Neanderthals. Right? Who sometimes we also call them cavemen. However, when we say Neanderthal in science, we're actually referring to this particular species or potentially subspecies. There's actually some argument there as to whether Neanderthals are a species or a subspecies of human. And it's worth noting that they do share 99.7% of their DNA with modern humans, which to put that into perspective chimpanzees share about 98.8% of their DNA with modern humans. So this is like a full percentage point closer to modern humans. So very similar DNA. Now humans are known as, Homo sapiens, which means wise man. And Homo sapiens are actually what we call, anatomically modern humans. People living today are thought of as a subspecies. We actually call ourselves Homo sapiens sapiens. Right? So our subspecies of modern humans just tacks on an extra sapiens. Right? So we're not wise man, but wise wise man, like super extra smart, I guess. And you can see that homo sapiens have inhabited the whole planet. We, our trajectory here is shown in red. We spread over Africa, made it up into Europe, Asia, Russia, crossed the Bering Strait into Alaska, down into the Americas, colonized all of the South Pacific region, Oceania, if you will, even went up into the Arctic region. So, our ancestors, I should say. I shouldn't take credit. Our ancestors colonized the whole planet. So, their forebears, the Neanderthals, now another term I want to briefly mention is Cro-Magnon, Cro-Magnon man. Right? Cro-Magnon people. Those are actually just early European Homo sapiens. So those are technically humans. Those are our direct ancestors, in essence. Now, in addition to this map, I also have this other cool chart that shows basically the presence of various species of the Homo genus, and their distribution, and also, like, when they were populating a certain area. So you can see we have Homo ergaster and Homo erectus. And you can see that Homo erectus started in Africa. Right? Spread out into Asia. So I know this chart might look a little confusing. Hopefully, you can kinda get the idea. I don't expect you to draw any terribly important conclusions from it. It's just there to add a little color to this story. Now, one thing I do want to point out though is that there is overlap between Homo neanderthalensis and Homo sapiens. That is to say that Neanderthals and Homo sapiens were contemporaries. They lived at the same time. However, there are no more Neanderthals. Right? Those guys disappeared at some point. Homo sapiens are everywhere now. And, you know, there's a lot of and also, you know, if you look at this figure you notice that the Neanderthals break off way before home sapiens break off. So they represent distinct lineages. Right? So what happened to the Neanderthals? That's a really big question. Where did they go? They were contemporaries with Homo sapiens, now there are none. There are many different theories as to why this is, including, you know, what they call assimilation. Essentially, Neanderthals interbred with Homo sapiens, and now we're all just kind of one species. They were essentially, Neanderthals were absorbed into Homo sapiens, which would give credence to the idea that they're actually just a subspecies, not a distinct species. Some theories go into places that are a little darker. I mean, for example, some people piggyback off the idea that there is an inherent violence in human nature. Right? That humans are innately violent organisms, and so people think that those old Homo sapiens may have actually, carried out genocide against the Neanderthals, that they actually wiped them out, and that's why they disappeared. So there's a whole range of explanations. I don't pretend to know enough to, you know, weigh in and say that I believe one is more likely than another. Though I do think they're very interesting. And I highly recommend that, if you're interested in this, you go check out some of those explanations, because it is fascinating stuff. That's our history. Right? So that's all I have for this video. Hopefully, this tickled your imagination a little bit, tickled your fancy, and I'll see you guys next time.

Here’s what students ask on this topic:

What are the main characteristics that define primates?

Primates are characterized by several distinct features, including large brains relative to body size, sophisticated visual systems controlled by the occipital lobe, and complex social behaviors. They also exhibit good parental care and, in many cases, have opposable thumbs, which allow for grasping and tool use. These thumbs can touch the front of the fingertips of each of the four digits, enabling fine motor skills. Primates are divided into two major groups: prosimians, which include lemurs and tarsiers, and anthropoids, which include monkeys, apes, and humans.

What is the significance of Australopithecus in human evolution?

Australopithecus is a genus of hominids that lived from about 4 million to 2 million years ago and played a crucial role in human evolution. One of the most famous species, Australopithecus afarensis, includes the well-known fossil 'Lucy.' These early hominids are believed to be ancestors of the genus Homo, which includes modern humans. Australopithecus species were native to Africa and exhibited both primitive and advanced traits, bridging the gap between earlier primates and later human species. Their evolution marks a significant step towards the development of bipedalism and increased brain size.

What are the differences between prosimians and anthropoids?

Prosimians and anthropoids are two major groups of primates. Prosimians, which include lemurs, lorises, and tarsiers, are considered more primitive and have features similar to early primates. They often have smaller brains and less complex social behaviors compared to anthropoids. Anthropoids, also known as simians, include monkeys, apes, and humans. They are characterized by larger brains, more sophisticated visual systems, and complex social structures. Anthropoids can be further divided into monkeys and hominids, with the latter including great apes like gorillas, chimpanzees, and humans.

What is bipedalism and which primates exhibit this trait?

Bipedalism refers to the ability to walk on two hind limbs, or feet. Among primates, humans (Homo sapiens) are the only species that are fully bipedal as adults, meaning they predominantly walk on two feet. Other great apes, such as chimpanzees, gorillas, and orangutans, can walk on two feet but primarily use their hands for movement, displaying a more quadrupedal locomotion. Bipedalism is a significant evolutionary trait that distinguishes humans from other primates and is associated with various anatomical adaptations, including changes in the skeletal structure of the pelvis, legs, and spine.

How did Homo sapiens spread across the globe?

Homo sapiens, or anatomically modern humans, originated in Africa and began spreading across the globe around 200,000 years ago. They migrated out of Africa, moving into Europe, Asia, and eventually reaching the Americas and Oceania. This global spread was facilitated by their ability to adapt to diverse environments and develop advanced tools and social structures. The migration routes included crossing the Bering Strait into North America and moving through the Middle East into Europe and Asia. This widespread colonization led to the diverse populations of humans found around the world today.