HUMAN EVOLUTION: GENUS HOMO

1. HUMAN EVOLUTION: GENUS HOMO

2. The following are misconceptions about evolution

3. Evolution involves only random changes—things happening by chance. • Random mutation is the ultimate source of genetic variation • But natural selection (the process by which only some variants survive) is not random • For example, streamlined body shapes evolved among some aquatic animals like sharks and dolphins. They could swim faster and therefore better capture prey and escape danger. • They were more likely to survive, reproduce, and pass on their traits to the next generation.

4. Evolution is about progress. Organisms are always changing and getting better, with humans as the culmination. • Evolution is not about organisms marching up a ladder of progress • Many organisms—including some mosses, fungi, opossums, and crayfish—have changed little over long periods of time • They are fit enough to survive and reproduce in their environment • Beetles and finches— changed and diversified greatly as they adapted to changing climates or new competitors. But that doesn’t mean they got “better” • Humans were definitely not the last organism to evolve. Numerous other species have evolved since the onset of human evolution

5. Evolution is directed toward an intentional goal or need • The process of biological evolution is not intentional • There is no evidence that evolution responds to what a species “needs” • Evolution does shape adaptations that enable organisms to survive and thrive in their environments • If an individual has a particular genetic variation, What occurs? • It will have more offspring and the population will evolve • Without this process of adaptation, or natural selection, a population may die out

6. FUN FACT!!!!!!!!!!!!! #1 • Why do we have so much white in our eyes? • Our eyes say it! • Get it! • No really do you get it? • Think here/now! • Compared to other primates, humans have huge ‘whites of the eyes’, or sclera. This means that humans can easily read each other’s gaze. In experiments, great ape infants usually follow a gaze only when the experimenter also turns his head. But human infants follow the gaze when the experimenter moves only his eyes. The whites of our eyes may help a lot in communicating with one another

7. Individuals can evolve during their lifetimes • Evolution happens to populations and species, not to individuals • An individual giraffe’s neck will not grow longer during its lifetime due to selection pressure to eat from taller trees (LaMarck) • If pressure for long necks exists, then individual giraffes with longer necks will survive and reproduce more often than those with shorter necks • They will produce offspring with longer necks, resulting in a population or species shift to giraffes with longer necks

8. Gaps in the fossil record disprove evolution • Science actually predicts gaps in the fossil record • Many species leave no fossils at all, and the environmental conditions for forming good fossils are not common • The chance of any individual organism becoming fossilized is incredibly small • New fossils are constantly being discovered. These include many transitional fossils—e.g., intermediary fossils between birds and dinosaurs, and between humans and our primate ancestors • Our lack of knowledge about certain parts of the fossil record does not disprove evolution

9. FUN FACT!!!!!!!!!!!!!!!!!!!! #2 • Your BRAIN sucks! • Literally. • Did you know that your brain makes up about 2% of your body weight… • but uses about 20-25% of your body’s total energy, just for its basic activity? • No wonder it’s good to eat nutritious foods that offer a lot of energy • The brain of a newborn baby is even more amazing, as it takes up about 60% of the baby’s energy as the brain grows at an astonishing pace

10. Humans are no longer evolving, and we can’t actually observe evolution in action • Human evolution usually occurs over so many generations that we can’t observe it • sometimes it happens over a relatively short span • Thoughts on what? • Ability to digest milk • Humans, are lactose-intolerant and cannot digest milk • Nearly 80% of adults of European ancestry have a gene that enables them to digest milk • Researchers think that this genetic change evolved in response to the spread of dairy farming 5,000–10,000 years ago

11. Humans are too complex to have evolved • Humans are the product of evolutionary processes that go back more than 3.5 billion years • We evolved new physical traits and behaviors on top of those inherited from earlier primates, mammals, vertebrates, and the very oldest living organisms • Human eye-Scientists think that 550 million years ago or more, a lightsensitive spot on the skin of an ancestral creature provided a survival advantage • Random changes over millions of years led to the evolution of a pit with a narrow opening, a retina, and eventually a lens

12. Mas Ojo • Eyes corresponding to these stages exist in living species. According to one calculation, only 364,000 years would have been needed for a complex eye like ours to evolve from a light-sensitive patch

13. FUN FACT!!!!!!!!!!!!!!!!!!!!!!!!! #3 • Why do we get goose bumps? • The body hair of all mammals automatically stands up when cold • Creating a fluffy layer of warmth. When we’re cold, the muscles around the hair follicles contract • a reflex left over from when our ancestors had long body hair. But since we don’t have much body hair, all we see are the goose bumps on our skin

14. If humans evolved from apes, there wouldn’t still be apes. • Humans and chimpanzees both evolved from a common ape ancestor that is now extinct • Based on genetic differences between humans and chimpanzees, scientists estimate that this common ancestor lived between 8 and 6 million years ago • Humans evolved a series of differences from this common ancestor; chimpanzees evolved their own unique series of differences • Like many other species that evolved from the same common ancestor, modern humans and modern chimpanzees continue to exist at the same time

15. FUN FACT!!!!!!!!!!!!!!!!!! #4 • Why do we have wisdom teeth? • When our back molars are impacted in our jaw, they don’t seem very wise! That’s funny (yes, Summer it is funny) • They’re the last teeth to come into place, and having them was helpful to our early ancestors who ate tough, uncooked foods that wore away their teeth. • But with cooking and making food softer, the size of our jaws has diminished, often with room for the last molars to form in the jaw…but – ouch! – not enough room to erupt. BOOM! That’s funny

18. How Did We Evolve? • 1) Before 5 mya: In Africa, our ancestral lineage and the chimpanzee lineage split. • 2) Before 4 mya: The hominid Australopithecus anamensis walked around what is now Kenya on its hind legs. • 3) >3 mya: Australopithecus afarensis (“Lucy”) lived in Africa. • 4) 2.5 mya: Some hominids made tools by chipping stones to form a cutting edge. There were perhaps four or more species of hominid living in Africa. • 5) 2 mya: The first members of the Homo clade, with their relatively large brains, lived in Africa.

19. Previous slide Cont. • 6) 1.5 mya: Hand axes were used. Also, hominids had spread out of Africa and into much of Asia and Europe. These hominids included the ancestors of Neanderthals (Homo neanderthalensis) in Europe andHomo erectus in Asia. • 7) 100,000 years ago: Human brains reached more or less the current range of sizes. Early Homo sapiens lived in Africa. At the same time, Homo neanderthalensis and Homo erectus lived in other parts of the Old World. • 8) 50,000 years ago: Human cultures produced cave paintings and body adornment, and constructed elaborate burials. Also, some groups of modern humans extended their range beyond Africa. • 9) 25,000 years ago: Other Homo species had gone extinct, leaving only modern humans, Homo sapiens, spread throughout the Old World.

20. Is this real, How do we know? • Primate Behavior (evidence #1) • Primates include lemurs, lorises, tarsiers, monkeys, and apes – a group of species that is well known for being social, smart, and very adept at using their hands. • They are also very vocal and communicative with the members of their social group. And they move around in a wide variety of ways, including sometimes on two legs. • Video 1 • Video 2 • Video 3 • Video 4

21. Follow the footsteps (evidence #2) • Footprints are a kind of evidence of behavior often called a 'trace fossil' - geological evidence of biological activity. This is in contrast to 'body fossils', fossilized remains from organisms' bodies. • Scientists can learn a lot from sites where human footprints have been found • Estimates of height, weight, and gait of the humans who made the footprints - which also tells us how many people made the footprints. • Features of the substrate that the footprints were formed in (was it soft? hard? wet? dry?).

22. Feet Continued • Aspects of the environment that the humans who made the footprints were living in, especially if there are footprints left by other animals. • Several human footprints sites have been discovered.

23. Mas Pies • Lets watch this video • Feet Found 800,000 years ago

24. Stone Tools (evidence #3) • Stone tools and other artifacts offer evidence about how early humans made things, how they lived, interacted with their surroundings, and evolved over time. • Spanning the past 2.6 million years, many thousands of archeological sites have been excavated, studied, and dated. These sites often consist of the accumulated debris from making and using stone tools.

25. Stone……… • Because stone tools are less susceptible to destruction than bones, stone artifacts typically offer the best evidence of where and when early humans lived, their geographic dispersal, and their ability to survive in a variety of habitats. • But since multiple hominin species often existed at the same time, it can be difficult to determine which species made the tools at any given site. • Most important is that stone tools provide evidence about the technologies, dexterity, particular kinds of mental skills, and innovations that were within the grasp of early human toolmakers.

26. Early Stone Tools • The oldest stone tools, known as the Oldowan toolkit, consist of at least: • Hammerstones that show battering on their surfaces • Stone cores that show a series of flake scars along one or more edges • Sharp stone flakes that were struck from the cores and offer useful cutting edges, along with lots of debris from the process of percussion flaking • This began 2.6 million years ago

27. The Birth of the hand axe • By about 1.76 million years ago, early humans began to strike really large flakes and then continue to shape them by striking smaller flakes from around the edges. • The resulting implements included a new kind of tool called a handaxe. These tools and other kinds of ‘large cutting tools’ characterize the Acheulean toolkit. • Homo Habilis made these

28. Hammerstone

29. Oldowan Tools from Lokalalei, Kenya

31. Stone Tools from Majuangou, China

34. Things start to change • These toolkits were established by at least 285,000 years in some parts of Africa, and by 250,000-200,000 years in Europe and parts of western Asia.   • We start to make points and attach them to spears and are able to expand quickly what our food sources are and what we can eat. We start to take off as a species. The beginning of us! • Homo Erectus made these

37. Cranial capacity for Genus Homo

38. How we Get food (evidence 4)

39. Experiments and microscopic studies show that early humans used the ends of these bone tools to dig in termite mounds. Through repeated use, the ends became rounded and polished. Termites are rich in protein and would have been a nutritious source of food for Paranthropus robustus (above). 1.5mya

40. Stone tool marks on this extinct zebra ankle bonefossillook like those made during butchery experiments. Scientists have made experimental stone tools and used them to butcher modern animals. There is a strong similarity between the marks their tools made and the marks on fossil animal bones, indicating that early humans used stone tools to butcher animals by this time. 2.6 MYA

41. Humans in Central Africa used some of the earliest barbed points, like this harpoon point, to spear huge prehistoric catfish weighing as much as 68 kg (150 lb)–enough to feed 80 people for two days. Later, humans used harpoons to hunt large, fast marine mammals. 90,000 years old

42. Hunting large animals was a risky business. Long spears  were thrust into an animal, enabling our ancestors to hunt from a somewhat safer distance than was possible with earlier weapons. Three wooden spears like this one were found at Schöningen, Germany, along with stone tools and the butchered remains of more than 10 horses. These spears are currently the oldest known wooden artifacts in the world. (400,000 years)

43. Stone or bone projectile points, like the one seen here, attached to spears or darts and enabled humans to exploit fast-moving prey like birds and large, dangerous prey like mammoths. 104,000 years.

44. The semicircular wound on this  fragment of a horse shoulder blade was made by a weapon such as a spear, indicating it was killed by early humans. Other horse bones from the same site have butchery marks from stone tools. 500,000 years old (England)

45. Technologies enabling plant and animal domestication, as seen in by these stone sickle blades from Dynastic Egypt and Ali Kosh, southern Iran, represent a turning point of human interaction with the environment.  4,650 - 4,150 years old (Egypt) and about 8,600 - 8,000 years old (Iran)

46. Early humans may have made bags from skin long ago. By around 26,000 years ago, they were weaving plant fibers to make cords and perhaps baskets. Some of the oldest known pottery from Japan’s Jomon culture, seen here, is about 18,000 years old. On the right 6,000 years old.

47. The earliest hearths are at least 790,000 years old, and some researchers think cooking may reach back more than 1.5 million years. Control of fire provided a new tool with several uses—including cooking, which led to a fundamental change in the early human diet. Cooking released nutrients in foods and made them easier to digest. It also rid some plants of poisons. Building shelters 400,000 years ago. Scientists found post holes and other evidence of multiple shelters at this site. 49 feet long in some areas!

48. At Qafzeh, Israel, the remains of as many as 15 individuals were found in a cave, along with 71 pieces of red ocher and ocher-stained stone tools. The ocher was found near the bones, suggesting it was used in a ritual. 101,000 years old.

50. Burial • Our ancestors often buried the dead together with beads and other symbolic objects. Burial rituals heightened the group’s memory of the deceased person. These rituals may imply a belief that a person’s identity extends beyond death.