[MUSIC] Welcome to this session of the Origins course, where we are going to take a look at the origin and evolution of primates, with special emphasis on the line it's leading to modern humans. My name is Bent Lindow. I am a vertebrate paleontologist and educator at the Natural History Museum of Denmark. In the following lectures, we will first review what is known about the origins and evolution of primates. And later we will look specifically at the evolution of modern humans, based on molecular evidence such as DNA. In this first video, we'll review the defining anatomical characteristics of various primate groups. We will also take a brief look at their closest living relatives. The second video will take us on a journey from the origin and through the evolution of primates during the last 65 million years. The previous session of the Origins Course examined climate change in Earth's history. And we will review the evolution of primates through the lens of prehistoric, global climate change, as this was a significant influence on the overall evolutionary pattern of primates. Thirdly, you will complete an assignment on your own. Using the Natural History Museum of Denmark's award winning online education resource, The Human Animal, you will study, measure and compare the skulls of various extinct and living hominids. As you do so, you will shed light on some aspects of the evolutionary processes leading to modern humans. What is a primate? We have now moved into the collection of recent mammals at the Natural History Museum of Denmark. Around me are various stuffed members of the primate order. The primates are a group of closely related mammal species, including amongst others lemurs, lorises, galagos, New World monkeys like this woolly monkey; old world monkeys such as baboons, and the great apes like chimpanzees and humans. All primate species share a number of of anatomical and molecular characteristics, which show that they all derive from a common ancestor species, which lived some time ago in the past. Chief amongst these anatomical characteristics are several which you can in fact find on yourselves, since humans are primates. First of all, nails. All primates possess nails, and some possess both nails and claws. Claws are curved sheets of keratin, coming to a sharp point, while nails are flat sheets of keratin, growing on of the top side of fingers and toes. Secondly, an opposable thumb. The first finger on the hand of all primates is set in opposition to the other fingers of the hand. Now this anatomical characteristic allows primates to have a firm grip on rounder surfaces, such as branches, and also to manipulate food and small objects very efficiently. Thirdly, highly mobile shoulder girdles. The shoulder girdles of primates are very mobile, and able to rotate effectively in several directions. This is an evolutionary development, which is well suited for climbing. It's in opposition to most other land mammals, who's shoulder girdles are basically restricted to a back-and-forth movement, which is a very strong and stable one for running and coursing. Fourthly, all primates have a bone cover behind the eye sockets. There's a bony bar or bone wall behind the eye socket of a skull of a primate. If you poke your finger through that eye socket of a primate skull such as a baboon, you will find that it hits a bony wall. This is unlike most other mammals. For example this wolf skull. If I put my finger through the eye socket of the wolf, it'll go straight into the fleshy area, where you can find the muscles of the lower jaw. This set of characteristics can be found in all living and extinct primate species. This is a simplified tree of relationships, also called a cladogram of various groups within the order of primates. We're going to journey through some parts of it as it were, and I will explain how. First of all, I do not want you to think of it as an evolutionary journey for some primitive small prosimian and up to the pinnacle of primate evolution, humans. Quite the contrary. Humans are just one species. One rather briefly living branch, amongst many interesting ones on the primate tree of relationships. The way we will go through the tree is by moving from branching point to branching point in the tree. At each branching point we will stop to examine the defining characteristics of each subgroup. And as we do so, we gradually zoom in on the group we are interested in studying in detail, the hominids and hominines, which includes our own species, Homo sapiens. At the bottom branching point of the primate tree, we find the characteristics which define all primates, as I mentioned before. Nails, an opposable thumb, highly mobile shoulder joint, and a bone cover or bone bar behind the eye sockets. We also find the first major division within primates, between the wet nosed primates and the dry nosed primates, also formally known as the Strepsirrhini and the Haplorrhini. The suborder Strepsirrhini, or "wet nosed" primates consist of the living lemurs, lorises and galagos, as well as the now extinct adapiforms. They have a number of shared anatomical characteristics, which show that they derived from a common ancestor in the deep past. All Strepsirrhini posses both claws and nails of the fingers, as well as a rhinarium, the moist naked area of skin around the nostrils. Furthermore, their skulls have a post orbital bar behind the eyes. And a toothcomb, which are closed set teeth in the lower jaw, used for grooming their fur. Also, strepsirrhine primates are able to produce their own Vitamin C. However, as humans do not belong to the strepsirrhine group, we will not delve further into it. The other main group within the primates are the dry nosed ones, or the haplorrhine primates. The Happlorrhini are also characterized by a number of shared features. They possess a dry nose, where the upper lip is not connected to the nose. Amongst others, this allows them to use it for a variety of facial expressions. But at the cost of a relatively inferior sense of smell. The Happlorrhini also have a fully developed bone wall behind the eyes, and have also lost their claws, and now only possess nails. Furthermore, happlorhine primates have lost their ability to produce their own vitamin C. Zooming further along the tree of relationships, we find the haplorrhini divided into two groups. The new world monkeys who all live in Middle and South America, and the old world monkeys, or Catarrhini, who live in Africa and Asia today. Humans belong to the catarrhine group, which amongst others is characterized by the shared trait of having just two pre-molars in the upper jaw. We have now zoomed onto our own superfamily within the primates. The apes or superfamily Hominoidea. The living representative of this group are gibbons, orangutans, gorillas, chimpanzees, and humans. The hominoid apes are united by a number of shared characteristics, separating them from the other primates. Chiefly, as can be seen in this orangutan skeleton, we lack tails. No long tail, and there are five fused vertebrae in our pelvis region. Now we have just zoomed on our own subfamily within the primate tree of relationships, the hominines, noting the defining characteristics on the way. Now we will zoom all the way out again, and briefly look at the closest living relatives of primates amongst the mammals. Analyses comparing molecular and genomic data have identified two living groups of mammals as being the closest to primates. Colugos and tree shrews. Of the two, the colugos are the ones which show the most genomic and molecular similarity to primates. Colugos are nocturnal, tree-living climbing animals, which inhabit the rainforests of Southeast Asia. The molecular data indicate that tree shrews are slightly more distant relatives to primates. Despite the name, they are not closely related to other shrews. They are omnivorous and mostly tree dwelling mammals. And all in all around 20 species of them live in Southeast Asia. This concludes the first video on systematics on defining anatomical characteristics of various primate groups. In the next video, we shall review the origin and evolution of primates, during the last 65 million years. [MUSIC]
