Human Evolution

Homo Neanderthalensis Homo Sapiens Homo Neanderthalensis Homo Erectus Homo Heidelbergensis Homo Habilis Homo Robustus Homo Ergaster Maybe add in an inquiry piece about asking students what makes humans unique, not only cognatively, but also physically? (upright, color vision, opposable thumbs etc) Australopithecus Africanus Paranthropus Aethiopicus Australopithecus Afarensis

Australopithecus anamensis 4.2 to 3.9 million years ago History of Man SPECIES TIME PERIOD Ardipithicus ramidus 5 to 4 million years ago Australopithecus anamensis 4.2 to 3.9 million years ago Australopithecus afarensis 4 to 2.7 million years ago Australopithecus africanus 3 to 2 million years ago Australopithecus robustus 2.2 to 1.6 million years ago Homo habilis Homo erectus 2.0 to 0.4 million years ago Homo sapiens archaic 400 to 200 thousand years ago Homo sapiens neandertalensis 200 to 30 thousand years ago Homo sapiens sapiens 200 thousand years ago to present

Earliest Ancestors Plesiadapis: 60 mya one of the oldest known primate -like mammal species Mainly lived on the ground However, it was a good climber. It was an arboreal quadruped. It was a tree-moving, 4-legged animal. What was the selective pressure for our ancestors to evolve? What happened about 65 mya? Why were they more fit than dinosaurs in the changing environment?

Primate Evolution Prosimians: 55 mya Generally nocturnal, generalized diets. Includes lemurs, lorises, bushbabies. Emergence of opposable thumb.

Short or absent tail (not prehensile) Primate Evolution New World Monkeys Lateral nostrils Prehensile tail Old World Monkeys Downward nostrils Short or absent tail (not prehensile) Why did they diverge? (Geographic isolation) Why did they diverge? Because they were reproductively and geographically isolated from each other by the growing separation between the African and South American continents. So as those two continents moved apart, climates changed and new selectional pressures arose.

Primate to Hominid Evolution Old World Monkeys New World Monkeys A subset of old world monkeys. All of the same differences from new world monkeys but an extra set of differences unique to hominoids. Hominoids Part of the superfamily Hominoids. Specifically include: - humans - orangutans - gorillas - chimpanzees Hominids

Hominid Evolution - Jaws: humans have a bowed jaw, Key Characteristics of Hominids (chimpanzees, gorillas, humans, and orangutans): - Jaws: humans have a bowed jaw, rather than a U- shaped. - Apes have diastema (spaces between teeth), we lack diastema. - Skeletal changes associated with bipedality - Cranial changes – development of forehead - Loss of brow ridges - Loss of sagittal crest – the ridge of bone running lengthwise along the midline of the top of many mammalian skulls. Define terms for them… hominid, homo, etc.

explanations for bipedalism. Hominid Evolution Key Characteristics of Hominids (chimpanzees, gorillas, humans, and orangutans): - Skeletal changes associated with bipedality Why? Climate/environmental change – forests began to shrink and savannah began to expand Define terms for them… hominid, homo, etc. Take a moment and write down possible explanations for bipedalism.

Hominid Evolution Key Characteristics of Hominids (chimpanzees, gorillas, humans, and orangutans): - Loss of sagittal crest – the ridge of bone running lengthwise along the midline of the top of many mammalian skulls. Define terms for them… hominid, homo, etc. Animals that do a lot of heavy chewing have a sagittal crest. It is needed for exceptionally Strong jaw muscles. Take a look at the sagittal crest on the right. It takes up a lot of room on the head and skull. If we no longer had the huge crest on the top of the head, what would be allowed to happen? We now have room to expand our skulls and, therefore, our brains!

Lucy: Australopithecus afarensis Hominid Evolution Lucy: Australopithecus afarensis 3.6 – 2.9 mya 1 meter tall Bipedal Partly arboreal Ape-like face with sloping forehead What was selected for? - Bipedalism Why? Environmental change. Let’s lead them to these ideas.

Hominid Evolution Australopithecines: 2.2 mya Bipedal, dentally similar to humans but smaller brain - Slender Some may have used tools Extension of cool, dry, savannah habitat

Hominid Evolution Now we start with the Homo line of Hominid Evolution The organisms we will talk about will have a two part name: Homo _______ Homo refers to our genus (which includes humans and our close relatives). The second part of the name identifies the species.

Hominid Evolution Homo habilis: 2.4 – 1.6 mya Similar to australopithecines Because face is still primitive Smaller face, jaw and teeth Larger cranial capacity Primitive stone tools

Hominid Evolution Homo Erectus: 1.8 – 0.3 mya Similar to habilis: protruding jaws with large molars, no chin thick brow ridges, a long low skull. More advanced tools. Spread from Africa to Europe and Asia.

Hominid Evolution Homo neanderthalensis: 230,000-30,000 years ago By 130,000 years ago, following a prolonged period of independent evolution in Europe, Neanderthals were so anatomically distinct that they are best classified as a separate species This is a great example of geographic isolation leading to a speciation event. Brain larger than modern humans. Midfacial area protruded perhaps an adaptation to cold. -Short and solid with short limbs because of the cold.

Hominid Evolution Homo sapiens sapiens: modern

Out – of – Africa Theory Modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus. - after Homo erectus migrated out of Africa, the different populations became reproductively isolated, evolving independently, and in some cases like the Neanderthals, into separate species - Homo sapiens arose in one place, probably Africa (geographically this includes the Middle East) - Homo sapiens ultimately migrated out of Africa and replaced all other human populations, without interbreeding - modern human variation is a relatively recent phenomenon We know this is true because every single human being across the planet has the same innate and learned behavior skill set. We can also interbreed successfully with humans across the planet.

So what are vestigial “organs”? Homologous structures of organisms that have seemingly lost all or most of their original function in a species through evolution. Can you think of any vestigial “organs” or behaviors? Tail bone Goose bumps in terms of defense. Infants will instinctively grasp any object which touches the palm ancestral primates would have had sufficient body hair for an infant to cling to, allowing its mother to escape rapidly from danger. Moro reflex Ear muscles Babies can swim before they walk Wisdom teeth Pruney fingers