primate classification

Summary

Highlights

• Kristen Lee Ral explains the basics of primate classification. 📝
• Primates have prehensile hands unlike dogs; they can grasp things. 🤚
• Prognathism varies significantly between primates and other mammals. 🐶
• The size of the brain case differentiates primates from other mammals. 🧠
• Key primate trait: forward-facing eyes improving depth perception. 👁️
• Lemurs, lorises, and tarsiers are prosimians; monkeys are anthropoids. 🐒
• Differences in dental structures highlight evolutionary adaptations. 🦷
• Monkeys and apes are differentiated by their locomotion methods. 🐒
• Human evolutionary progress includes notable skeletal adaptations. 🚶‍♂️

Key Takeaways

• Primate hands are prehensile, while dogs lack this feature. 🐒
• Primates have forward-facing eyes for better depth perception. 👀
• Prehensile tails are a feature in some primates, aiding in arboreal navigation. 🌳
• The primate classification starts broad and narrows down to specific groups. 🗂️
• Human evolutionary traits include larger brains and bipedal adaptations. 🧠
• Taxonomy can vary, but the basis remains the same for primates. 📚

Overview

Chapters

• 00:00 - 00:30: Introduction to video and purpose The chapter introduces Dr. Kristen Lee Ral, a professor of human evolutionary biology at the University of California Davis. The introduction is set against a backdrop of music and laughter, signaling a light and engaging entry into the topic.
• 00:30 - 05:00: Basic primate taxonomy and distinguishing characteristics from other mammals This chapter provides an introduction to primate taxonomy, aimed at beginners. It compares the basic skeleton structure of primates with other mammals, specifically comparing a monkey to a dog. It highlights the fundamental differences in taxonomy and encourages further study for those interested in more advanced learning about primates.
• 05:00 - 15:00: Comparing Prosimians and Anthropoids Primates have the unique feature of prehensile hands, allowing them to grasp and hold objects, unlike dogs that lack this ability.
• 15:00 - 20:00: Differences between Platyrrhines and Catarrhines Chapter 1: Differences between Platyrrhines and Catarrhines The chapter discusses distinguishing features of primates, including their flat nails that protect the finger tips. Another distinguishing trait is the flatness of the face compared to other animals like dogs, which have elongated snouts—an aspect known as prognathism. While dogs are more prognathic, monkeys display less prognathism. Additionally, the chapter touches upon the brain structure, mentioning the brain cage or skull area, suggesting further explanation in subsequent parts.
• 20:00 - 25:00: Differences within Catarrhines: Cercopithecoids vs. Hominoids This chapter discusses the differences in physical and anatomical features between Cercopithecoids (Old World monkeys) and Hominoids (apes and humans) within the Catarrhini group. The focus is on the relative size and positioning of the brain within the skull. Primates, including Hominoids, have a larger brain in relation to the skull size compared to non-primate mammals like dogs. Additionally, primates have forward-facing eyes, which differ from the side placement of eyes in mammals like dogs or deer. These features are important for understanding the distinct evolutionary paths and adaptations of Cercopithecoids and Hominoids.
• 25:00 - 35:00: Differences within Hominoids: Lesser Apes, Great Apes, and Humans In this chapter, the discussion centers on the differences within the hominoids, which include lesser apes, great apes, and humans. A key focus is on the placement of eyes and its implications: while some animals (non-primates) have eyes on the sides of their heads for a broader visual field to detect predators, primates, including humans, have eyes positioned at the front of the skull. This adaptation is favorable for overlapping fields of vision, which enhances depth perception, a trait beneficial for an arboreal, tree-dwelling lifestyle.
• 35:00 - 40:00: Understanding bipedal apes and human anatomy This chapter explores the anatomical and perceptual adaptations of bipedal apes and humans with a focus on arboreal lifestyles. Key traits discussed include depth perception, grasping hands, and the presence of nails instead of claws, highlighting their significance for living in tree-dense environments. The importance of visual acuity in preventing falls from branches is emphasized, linking anatomical traits directly to survival and lifestyle habits among early bipedal creatures.
• 40:00 - 42:00: Conclusion and taxonomy visualization The chapter discusses the evolutionary changes in animals, particularly focusing on the relationship between the sense of vision and sense of smell. As the sense of vision became more significant for survival, certain animals saw a reduction in the size of their snouts. In contrast, animals like dogs, which rely more heavily on smell, exhibit elongated snouts to accommodate extra sensory organs. Dogs lack protective enclosures for their eyes, highlighting their anatomical differences from primates who possess hardened structures around their eyes.
• 42:00 - 43:00: Closing Music The chapter 'Closing Music' concludes with a discussion on the unique traits of primates that distinguish them from other mammals. One such trait is the protective bony structure around their eyes, highlighting the importance of vision. The chapter compares different types of eye enclosures in primates and notable differences with other mammals, such as the presence of a clavicle, which all primates have and some mammals, like dogs, do not.

primate classification Transcription

• 00:00 - 00:30 [Music] [Laughter] [Music] hello I'm Dr Kristen Lee Ral I teach human evolutionary biology at the University of California Davis this
• 00:30 - 01:00 video is a basic introduction to the primate taxonomy and it's intended for beginning students but the system of primate classification can get a lot more detailed than what's presented here so if you're interested I highly encourage you to pursue more advanced study I hope you enjoy this guided tour of our fascinating order the primates so the first thing we're going to look at here is to compare a monkey which is of course a primate to a dog which is a mammal but obviously not a primate so what sort of differences can we see between skeletons so the first important
• 01:00 - 01:30 thing that you'll notice is that primates have prehensile hands which means they can grasp and hold onto things just like the spider monkey is the dog does not have prehensile hands right dogs can't actually grasp things with their hands primates also have something called Penta which means you have five digits on your hands and feet all primates have that characteristic they also have nails on their digits instead of claws like the dog has claws
• 01:30 - 02:00 right primates have nails which are flattened out and serve to protect the tip of the finger some other things you might notice that distinguish primates is sort of the flatness of the face right as opposed to the dog the snout is elongated out of the front and the elongating in the front of the face is called prognathism right and so the dog is more prognathic and the monkey is less prognathic you can also see that the brain cage the area in which the
• 02:00 - 02:30 brain is actually contained within the skull is quite a bit larger in relation to the overall skull than it is in the dog the brain case relative to the size of the skull overall is diminished in size relative to the primate other important characteristics of primates are the forward-facing eyes rather than uh on the dog they're a little bit more to the side and you can imagine other types of mammals like um deer or oxin something like that their
• 02:30 - 03:00 eyes are actually on the sides of their head and that gives them uh Vision around uh towards the back of themselves which could be important um for them to avoid Predators primates on the other hand the eyes are rotated towards the front of the skull and this gives them overlapping fields of vision which is good for depth perception and improves depth perception so that's related to a whole cluster of traits that go along with a lifestyle of living in the trees which is called an arboreal lifestyle right live in the trees so depth
• 03:00 - 03:30 perception becomes very important when you're jumping from Branch to Branch right you wouldn't want to if your depth perception is vad you might miss the branch and fall to the ground which wouldn't be good at all right and so these other traits as well the grasping hands the claw the nails instead of claws all of these things are related to um a lifestyle of of living in the trees these are all adaptations to an arboreal lifestyle and so the importance of the eyes for that type of lifestyle is related ated to the reduction in the
• 03:30 - 04:00 size of the snout because as the sense of vision became more important than the sense of smell the eyes are emphasized and the snout is reduced as you know dogs have excellent sense of smell and are often more reliant on their sense of smell than their sense of vision and so you have an elongated snout that allows for extra sensory organs inside the snout um dogs do not have an enclosure to protect their eyes right their eye would be there and there sort of soft flesh around the eye primates have a
• 04:00 - 04:30 protective bone around their eyes and this is related to the importance of of the sense of vision and so um there is a bony enclosure around the eye when we look at different kinds of primates we'll distinguish the different types of enclosures around the eye so that's just an overview of what makes primates different from other mammals and the traits that they have one other trait that I'd like to point out is the collar bone the clavicle right primates always have a clavicle not all mammals have a clavicle right like this dog does not
• 04:30 - 05:00 have a clavical cats do not have clavicles right so those are some various features that distinguish primates from other types of mammals here is a basic primate taxonomy primate classification can be thought of as a series of levels each one getting more and more specific every specific category also belongs to the larger more General categories that are above it so let's look at these taxonomic levels one at a time we'll start with the most basic primate distinction prosimians
• 05:00 - 05:30 which include lemurs lorises and Tarsiers and the anthropoids which include the monkeys and the [Music] Apes okay so now let's look at the different types of primates the first initial distinction is between something called prian and all the other kind of primates which are called anthropoids and we'll get to the different kinds of anthropoids in a moment
• 05:30 - 06:00 so we have our Pro smans here is a galago also a bush baby and here we have a monkey called a Tamarind and also a lemur skull here at the bottom a lemur is a prian as well so some of the things that distinguish prosimians from anthropoids in terms of their uh skulls is um you notice that the prian has is more prognathic has more of a snap the anthropoid has a flatter face right and you can see that if I hold the
• 06:00 - 06:30 uh the prmium the Lemur next to the anthropoid you can see how much longer this snout is on the prmium than the anthropoid other differences again is the uh increased brain size the uh actual brain case part of the skull is enlarged relative to the rest of the skull in the anthropoid the brain case size relative to the skull in the prmium is a little is smaller right and you can see that when I hold the Lemur skull up the size of the brain case relative to
• 06:30 - 07:00 how long the snout is compared to the Tamarind here whose snout is very much reduced but the brain case is enlarged one other difference we can notice in the skulls between prosimians and anthropoids is that prosimians have something called a tooth comb many prian have a tooth comb and it's just what it sounds like the incizors in the lower jaw are quite thin like the teeth on a comb and they project forward and this is what allows them to clean themselves with that projecting forward uh comb
• 07:00 - 07:30 like feature of the bottom ins sizers anthropoids don't have tooth Combs so if you ever hoen across a primate and you notice they have a tooth comb you know it's a prian and not an anthropoid so another difference that you can notice between the anthropoid primate and the prmium has to do with that bony enclosure around the eye that I talked about so the prmium has what's known as a postorbital bar this piece of bone that goes behind the eye to protect it sort of along the side of the eye but
• 07:30 - 08:00 you notice that you can still see through it's not completely enclosed there's an opening there that's different than the anthropoid primate who has both the postorbital bar like the pryan but also what's known as a postorbital plate behind the eye it's completely enclosed in bone you can't see through that right it's enclosed with bone unlike the Lemur the proon here that you can see there's a lot of open space there it's not totally enclosed so this is another difference between prosimians and anthropoids
• 08:00 - 08:30 prosimians only have the postorbital bar anthropoids have both the postorbital bar and the postorbital plate one thing to remember is that taxonomies can vary and some anthropologists prefer a slightly different classification at this most basic level the difference between the two taxonomies is very simple and it has to do with where you group The tarer if you place the tarer with the Lemur and lorises then we call that group prosimians and everything else is
• 08:30 - 09:00 an anthropoid but if you place the tarar with the monkeys and apes we call that group Haines and the Lemurs and loris's strep serines returning to our original classification scheme we just saw the differences between prosimians and anthropoids now let's look within the group of anthropoids which can be divided into two categories plines which are the new world monkeys and catarin which are the old world monkeys and the
• 09:00 - 09:30 Apes including humans one difference between plines and catarin has to do with the shape of their noses plines have sideways facing round nostrils that are widely spaced catarin have downward-facing oval nostrils that are narrowly spaced the second difference is in the dental formula plines have three premolars but catarin only have
• 09:30 - 10:00 two a third difference is that some plates have prehensile tails that can grasp things like branches catarin do not have prehensile tails so those are some key differences between plines and catarin next we'll look within the category of catarin which can be divided into two different groups on the one hand we have copds which are the old world monkeys and on the other we have hominoids which are the Apes and people
• 10:00 - 10:30 [Music] okay so now we looked at the difference between plines and catarin now we're going to look within the group of catarin we've got copds which are the old world monkeys and hominoids which are Apes including humans so some very uh noticeable differences between monkeys and apes overall monkeys and AES has to do with their man of locomotion right so monkeys are quadrupedal either terrestrial
• 10:30 - 11:00 quadrupeds meaning that they get around on all fours on the ground or arboreal quadrupeds meaning that they get around on all fours on the tops of branches apes are what's known as brachiators meaning that they swing underneath the branches by their for liims right for liim suspensory motion is what this is called um and that has a suite of traits altered in the skeletons to allow them to do that versus standard quadrupedal so let's look at what those
• 11:00 - 11:30 things are one thing you'll notice is the length of the lumbar region which is the lower back from the last rib to the top of the hip bone the lumbar region and the quadrupedal U copine the monkey obal monkey is longer than it is in the brachiating ape in this case we have a gibbon a gibbon is a lesser ape or hobes the lumbar region in the AE is shortened um you'll notice also that monkeys have ta
• 11:30 - 12:00 Apes do not have tails right these are critical difference um another thing you'll notice is the orientation of the form and Magnum the hole at the base of the skull where the spinal column enters into the skull in a quadrip it's more towards the back of the skull where if you're on all fours right to be able to see forward your spine has to come into the back of your skull if you're hanging from limbs the orientation of the spinal column into the skull is more at the bottom because you're facing you're upward and
• 12:00 - 12:30 to keep your face facing forward so the placement of the form of Magnum on the skull is a difference between um the copid and the hominoid another difference you'll notice is the orientation of the scapula or the shoulder blade so in the monkey the shoulder blade is more on the side of the body in the homonid it's rotated towards the back of the body another difference you'll notice is the clavicle is elongated in the homonid
• 12:30 - 13:00 turn this sideways so you can see the length of the clavicle it's longer in the ape and shorter in the monkey um some also differences in the four limbs that you'll notice are that the monkey has an elongated elbow this piece of bone that sticks out extends at the base of the elbow it's called the elecron process um theer electron process specifically because this is Thea bone and this is a longer one than
• 13:00 - 13:30 we see in the homonid um which is has no such extension at the end of the elbow now all of these sorts of traits have to do with getting around suspended from the trees so having a shorter lumbar region and no tail and also having relatively long for limbs compared to your hind limbs um helps with the momentum when you're swinging under the trees from your for limbs a shortened base and a longer top makes the swinging motion more smooth smooth it's also
• 13:30 - 14:00 better to be able to completely extend your arm to be able to swing you can imagine trying to do monkey bars with your arms bent you have to be a lot stronger so the full extension of the arm is helpful now if you have this elongated elbow bone that's going to prevent you from being able to extend your for limb the monkey it's good to have this extra piece of bone because they actually Bear their weight on their for limbs cuz they're quadrupeds and that gives extra stability to the Elbow when you're putting weight on them so those are why the you see the differences in the
• 14:00 - 14:30 elbows in the monkey the length of the for limb and the length of the high limb are relatively equivalent that helps them when they're getting around on all fours right in Apes the length of the for liims is greatly longer than the length of the hind Limbs and that has to do with being able to swing under the trees um some other things you'll notice um differences between hominoids and copics have to do with their teeth specifically the molers so ccops the old
• 14:30 - 15:00 world monkeys have what's called a bodon molar bodon by meaning two l meaning a sort of a a a raised bump right a loaf of sort of like um so two loafs right and da being teeth so a bilophodont Moler is a Moler that has two loaves to it right one here and one here a ridge down the middle now that is a special adaptation for the diet that copine monkeys have hominoids have what's known as a y5
• 15:00 - 15:30 molar and it gets its name because it has five sort of projecting cusps points tips on the Moler five of them and they're in a configuration two on one side and three on the other that allows you to draw a y in the grooves as somebody has done on our model here so hominoids y five molars copines bodon MERS and those are some of the key differences between Circ capoid which are old world monkeys and
• 15:30 - 16:00 hominoids which are the Apes so there are a lot of skeletal differences between copics and hominoids and many of these have to do with the fact that the Apes have a complex of traits related to brachiation within the homonid group there are hobes the Gibbons and the cangs which are called the lesser apes because of their small body size we saw a gibbon skeleton at the last station and the hominids which are the great apes The Chimps gorillas and orangutans
• 16:00 - 16:30 and the bipedal Apes humans and their bipedal ancestors so let's look within this group of hominids at the great apes the pongids and the homins the bipedal Apes so at this station we're just going to look at haroids the Apes and what makes the difference between different types of Apes right so there are lesser
• 16:30 - 17:00 apes which we don't have represented here the Gibbons and the cangs you saw at another station and then there are great apes um oritan gorillas chimpanzees and humans so let's compare uh the just the skulls at this point so a few things to notice is uh the brain case size right so in the back row here we have male specimens and on the front row we have female specimens we have Pongo orangutans
• 17:00 - 17:30 gorilla gorillas pan chimpanzees and Homo humans Homo sapiens so if we look at the brain case size again as we've looked at other stations the size of the area that actually contains the brain relative to the overall size of the skull if you look at these great apes the male oritan and the male gorilla right and also the male chimpanzee so get a sense of that then if you compare the human look how much larger the brain case size is relative to the size of our
• 17:30 - 18:00 skull it's almost the whole skull right compared to other gr AES so that's one major difference the great apes all have relatively similarly sized brains around 400 450 CC's modern humans a great deal larger 1,400 1500 cc's somewhere in that approximate range so almost three times the size of the other great apes another difference to notice are the size of the canine teeth right and so one not difference we'll notice if
• 18:00 - 18:30 you look at all the male specimens is just how large the K9 teeth are in relation to the size of the other teeth right and even the chimpanzee right the procanes project they're very obvious compared to the other teeth if you look at a human the canines are pretty much the same size as all the other teeth in the mouth right it's hard to even tell which one's the canine you have to count in sizers canine prol right so reduced canines greatly reduce canines in the humans relative to the other Apes now
• 18:30 - 19:00 there's a different type of um of another thing that's interesting to look at in terms of the size of canines and that's sexual dimorphism so remember that sexual dimorphism is differences between males and females in the forms right dimorph two different morphs um between males and females this can take multiple forms we'll look at a couple here some we'll look at the canine teeth right so if you compare the size of the canines and the female gorilla compared to the size of the can in the male gorilla quite a bit larger in the male
• 19:00 - 19:30 than they are in the female and that's very typical across the primate order if males have enlarged canines the female canines are often reduced relatively speaking so we'll look at the male gorilla as a perfect example of a Sagal Crest it's the piece of bone I'm holding right here this Ridge almost like a fin or a mohawk on the top of the head is called A sagittal Crest now the function of the sagittal Crest is to Anchor the jaw muscles right the jaw muscles would attach up here they come up through the
• 19:30 - 20:00 zygomatic Arch or the cheekbone come up through that opening and attach at the top of the skull now you only need this large sagittal Crest if you have very large powerful jaw muscles which this male gorilla has and so you can see the sagittal Crest on the male orangutan as well quite a bit smaller than it is on the gorilla but still noticeable um now we look at the dimorphism the sexual dimorphism between males and females here's the male orangutan here's the female orangutan the top of her head is
• 20:00 - 20:30 quite smooth there's no sagittal Crest right the male has the sagittal Crest so they're dimorphic in that regard gorillas are also quite dimorphic in the fature of the sadal crest right the female has just a little inkling of a of an increased amount of bone there at the top compared to the male of course which has this enormous fin of bone on the top of his head um humans are not really dimorphic in that regard neither males nor females
• 20:30 - 21:00 this is a female this is a male neither one has A sagittal Crest humans are characterized by this very round uh globular head right very smooth none of these bony tuban that we see on many of the other types of great apes particularly the males right the brow Ridge these sorts of things humans do not have all those extra pieces of bone um so another thing is also the prognathism you'll notice if you look at the great apes and the degree to which
• 21:00 - 21:30 if you look from the profile the degree to which the face um extends outward prognathism right um is reduced compared to other types of primates but compared to the human the flat-faced human we have nearly no prognathism at all we have extremely flat faces compared to other great apes like this chimpanzee right so you can see the prognathism uh orangan gorilla and chimp all have increased prognathism relative
• 21:30 - 22:00 to the human which is reduced prognathism so a key difference between bipedal Apes like this homin Homo sapiens and other types of great apes that are not bipedal like chimpanzees has to do with the shape of the pelvis here's a chimpanze pelvis and you'll notice some obvious differences um first of all the length the overall length from top to bottom it's quite a bit longer than in the
• 22:00 - 22:30 bipedal human from top to bottom it's the pelvis is shorter also the shape of this iliac blade um is flattened out in the chimpanzee but has a curved shape in the biped it almost forms a dish-like bowl shape of the pelvis in the biped some of the uh factors that have to do with the repositioning and reshaping of the pelvis in the biped have to do with the attachment sites for
• 22:30 - 23:00 abductor muscles things that help you keep your balance as you're walking around on just two legs unlike the chimpanzee so in the homin the homo sapian biped the muscles attached on the side from the top of the hipbone to the side this way whereas in a quadrip or a brachiator or knuckle Walker um like a chimpanzee the muscle attachments are across the back instead of on the side as they are on the biped another difference between the two having to do with bipedality is in the
• 23:00 - 23:30 structures of the feet so as you know chimpanzees feet look quite a bit like their hands they have opposable big toes they maintain the grasping ability the prehensile of the foot like the hand humans who are bipedal use their feet to Bear their body weight as they get around now the big toe is no longer opposable out to the side here and able to um uh move in relation to the other
• 23:30 - 24:00 toes um it's now in line with all of the other toes um and that has to do with uh greater efficiency as the foot is moving across the ground if you had a big toe sticking out to the side that would interfere with the smooth efficiency of uh the the motion of the foot for a bip head and that completes our taxonomy of the living primates here's another way to visualize this classification system as a series of nested boxes remember that each small smaller box also belongs to the larger boxes that contain it so
• 24:00 - 24:30 we have all the primates in one big box which we can then separate into prian and anthropoids within the anthropoid group there are plines and catarin and within the catarin there are copds and hominoids hominoids can be divided into hyades and hominids and hominids can be divided into pongids and hominins
• 24:30 - 25:00 this all might seem complicated to you now but keep studying be patient you'll get the hang of it [Music] [Music]
• 25:00 - 25:30 n [Music]