Exam 4 Study Questions: 1. Write a short statement on Homo erectus. Be sure to 1) identify at least one important distinctive feature each of the head, chest and femur of H.erectus and discuss the way in which each of these structures is different from that found in modern humans; 2) discuss what the anatomy of H.erectus tells us about this species: a) diet and b) locomotor capabilities. * Head: H.erectus had a significant increase in brain size with a skull vault of about 1000 cc. This size is bigger than all the previous members of the genus Homo and similar to that of humans. * Chest: H.erectus had narrow rib cages similar to modern humans’, which indicates that H.erectus did not have complex guts like Lucy’s and was probably meat eaters. * Femur: H.erectus had extremely long femoral necks which were ever longer than humans’ which indicated that they might be even more adapted in bipedalism. * Diet and Locomotion: The anatomy of H.erectus indicates that their diet probably contained mainly meat and they are probably no longer foliovores. Like modern humans they relied on high protein, meat concentrated diet. Their means of locomotion was a kind of bipedalism probably even more efficient than modern humans’.

2. Identify what it means to be a) altricial, b) precocial and c) secondarily altricial. Then discuss the evidence that leads researchers to believe that H. erectus was secondarily altricial. * Altricial: Born helpless, the babies need time in a nest/den with mothers. For example kittens or puppies. * Precocial: Babies are able to walk and see after a short time after birth, for example horses and zebras. * Secondarily altricial: 2 fetal stages. Conception to 9 months, and in the first year of life fetus grow extremely fast—a lot of weight gain and brain growth. * H.erectus was believed to be secondarily altricial because being secondarily altricial is beneficial in animals with a larger rain because it allows for the offspring to be born when its head can fit through the birth canal and develop further after birth. 1) the ratio of the size of birth canal to total pelvic area was about 87% compared to that of normal human. 2) the brain size of H.erectus was pretty big at adulthood, which indicated significant brain growth after birth.

3. Discuss how bones grow and how we know that KNM-WT 15000 was not a full grown adult. 1) Bones were born in “pieces” with unfused parts at both ends. During adolescence the epiphysis (bone ends) is not fully attached to the diaphysis (bone shaft). As an individual grows to become adult the metaphysis (growth plate) extends and eventually fully joins with the epiphysis and adult bones thus wouldn't show growth plates anymore. 2) KNM-WT 15000 the “strapping youth” was known to be a juvenile because he had incomplete epiphyseal closure (growth plate is still visible) and only had the second molar in.

4. A) Briefly contrast the postcranial anatomy of Neanderthals with that of anatomical modern humans; and then; b) discuss what is it about Neanderthals that leads researchers to think that these individuals were cold-adapted. Make sure toe cite evidence to back up your points. * Postcranial anatomy:
Neanderthals were pretty short, heavy and stocky—they had heavily built bodies and heavier bones. A Neanderthal the same size of a modern human would have weighed 30% more.
Neanderthals had more well-developed shoulders and rotator cuff than humans; the shaft areas in their arm bones are reinforced.
Neanderthals had a more barrel-like chest than humans.
Neanderthals had shorter limb proportions than that of human. * Cold-adapted:
Neanderthals had shorter and stockier built limbs which helped to preserve heat. The crucial index (the length of the tibia divided by the length of the femur) is a way to test out cold-adpation, and it showed that Neanderthals had really short limbs compared to their barrel chest and indicated that they are cold-adapted.

5. Discuss two pieces of evidence indicating that Neanderthals were capable of bringing down big game. * The bones of large animals were over-represented at Neanderthal sites relatively to their frequency in the ecosystem. * All the animals at the Neanderthal sites were in their large, prime adulthood and medium built state. There weren’t killed by natural disasters since the fine and strongs were more represented than the sick and olds.

6. Choose either the “Pre-Neanderthal” or “Pre-Sapiens” hypothesis and write a short statement defending that theory. For full credit be sure to a) identify the theory itself, including what the hypothesis states about the genetic contribution of Neanderthals to anatomically modern humans; b) site morphological evidence c) evidence from growth and development and d) genetic evidence to back up your points. * Theories:
The “Pre-Sapien” hypotheses stated that Neanderthals were a separate spies that went extinct, that there were no interbreeding and no genetic contribution from Neanderthals to AMHs. * Morphological evidence:
Neanderthals are different from modern humans for their: * Extremely large brown ridge * Long and low skull * Have no chin * Heavily built bodies and bones * Short limb proportions * Occipital bun * Evidence from growth and development:
Neanderthals were three years more sexually mature. They grew on a different scale and would have reached maturity at 15. They had no growth spurt, and would already have some of the proportions in uteral. Thus AMH are not similar to Neanderthals in early phases at all. * Genetic evidence:
Neanderthals’ mitochondrial DNA and AMH’s mtDHA branched off about 300,000 years ago. There were few similarities.
From the Neanderthal genome we can see that they only share 1-4% of their DNA with non-Africans, this small overlap is not representative of iner-breeding, but rather that modern humans and Neanderthals are two branches from the same bush.

7. Identify: a) What is mtDNA? b) Who was mtDNA “Eve”? c) What exactly is meant by the term “molecular clock” and d) discuss one potential problem with the molecular clock. Be specific. * MtDNA is the DNA found in the mitochondria instead of the nucleus. It is only passed through the maternal line. This DNA has a high mutation rate about 5-10 times faster than nuclear DNA. * mtDNA Eve is the believed female that all the mitochondrial DNA is traced back to, since all of us living on this planet share some features in our mtDNA. * The term “molecular clock” is the assumption that mtDNA mutates at a constant rate. Other than mutation, it cannot be sped up or slowed down by natural selection. * One potential problem with the molecular clock is that it is dependent on fossil and paleontological evidences. The dates of the molecular clock are subjected to changes upon new discovery and we would have to recalibrate the clock.

8. Contrast “Out of Africa” with the Multiregional model for the spread of anatomically modern humans around the globe. Your answer should a) identify the major points of both hypotheses; and b) provide at least ONE piece of evidence for each hypothesis that, if found, would support that hypothesis. * “Out of Africa” or Replacement:
This theory states that a relatively recent common population of H.sapiens differentiated regionally in Africa and then expanded out of the continent replacing all other populations of H. erectus and archaic Homo in Asia and Europe. * Multiregional model:
Recent human radiation is a product of the early to middle Pleistocene radiation of Homo erectus out of Africa. These populations gradually evolved into the modern populations living the approximately the same regions today. * Evidence—“Out of Africa”: transitional fossil records should be only restricted to Africa. Anatomical and behavioral discontinuity should be found outside of Africa. For example, if an abrupt change of H.erectus and H.sapiens and their tool cultures was found in regions outside of Africa, this would support the “Out of Africa” theory. * Evidence—Multiregionalism: there should be a continuity form between H.erectus and H.sapiens and transitional fossils should be found outside Africa. The anatomical land behavioral should follow a local sequence.

9. Discuss the chemical factors that combine to influence an individual’s “constitutive pigmentation”. Then provide a short discussion of how natural selection, acting both in and away from the tropics, produces a gradient in human skin pigmentation. * Physical and chemical factors:
Melanin, Hemoglobin and Carotene.
Melanin is a brown pigment secreted by melanocytes. Everyone has the same amount but depends on activeness and size of the cells. They create deeper and darker colors.
Hemoglobin is the red color in our blood and gives the skin a pink color.
Carotene is exactly the same pigmentation in carrots and gives the skin a yellowish color.
The thickness of the skin can also cause it to appear more yellow. * Gradient in human skin pigmentation:
The range of variation in human skin color is manipulated according to absorbance and tolerance of UV light, since too much UV light can damage our DNA.
In the tropics it is important for humans to protect themselves from the sun, thus more melanin that forms in larger clumps is selected for in the tropic to protect these populations form the sun’s damaging rays, this causes these populations to have darker and more tanned skin.
In the far north and away from the tropics, there are less sunlight available thus it is important for people’s skin to aid them in absorbing sunlight. Lighter skin with less melanin is selected for in these regions.
In between the tropics and the far north and south, the amount of sunlight varies in a gradient and therefore skin colors vary following this gradient.

10. In class we discussed three major lines of evidence supporting the conclusion that race is not a biologically meaningful category. Identify each of these 3 lines of evidence, and then add to this a short statement discussion why the conventional racist scale is really nothing more tat a resurrection of Aristotle’s “Great Chain of Being”. * 3 major lines of evidence: 1) Human variation is often clinally distributed, and not discretely distributed. For example from Africa to Wales, the change in skin color is gradual, not sudden. 2) When you use different traits to group people, you would get different groups. 3) There is more genetic variation among local groups than actually separating them from one another. * Racist scale:
The idea of race and human populations is similar to Aristotle’s “Great Chain of Being” since that theory states that all organisms can be “ranked” on a ladder-like scale of perfection and purity. Humans throughout history have believed that white skin is the purest and therefore the highest Great Chain of Being and dark skin colors with being the least pure and the lowest. However no biological evidence supports the betterness of a specific skin color, thus there is no reason for any of them to be considered the “purest”. Different populations have interbred consistently throughout history, meaning that not one racial category is more pure than another but rather we are all the same.