1. Discuss the evolutionary trends in the genus Homo . Start with the transition

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Question

1. Discuss the evolutionary trends in the genus Homo. Start with the transition from early Homo to Homo erectus and end with the Neandertals. Be sure to include the temporal and geographic distributions of the various species of Homo.

2. Discuss the two main hypotheses that have been used to explain the origin and dispersal of modern humans.

3. What is the adaptive value of dark skin tones in equatorial regions such as Africa? What evolutionary pressure caused a lightening of skin tones away from this area?

4.Explain the way a woman’s diet during pregnancy can have an impact on her future child and grandchildren.

Explanation / Answer

1. Although taxonomy and phylogenetic relationships of the earliest known representatives of Homo, remain obscure, advanced techniques for absolute dating and reassessments of the fossils records give a well acceped unilineal model of human evolution, in which Homo habilis succeeded the australopithecines and then evolved via H. erectus into H. Sapiens.

Here below, temporal and geographical distribution of genus Homo populations in a tabular form is shown:

Species

Temporal range

Habitat

H. habilis

2,100 – 1,500

Africa

H. erectus

1,900 – 70

Africa, Eurasia (Java, China, India, Caucasus)

H. rudolfensis

1,900

Kenya

H. gautengensis
also classified as H. habilis

1,900 – 600

South Africa

H. ergaster
also classified as H. erectus

1,800 – 1,300

Eastern and Southern Africa

H. antecessor
also classified as H. heidelbergensis

1,200 – 800

Spain

H. cepranensis
a single fossil, possibly H. erectus

900 – 350

Italy

H. heidelbergensis

600 – 350

Europe, Africa, China

H. neanderthalensis
possibly a subspecies of H. sapiens

350 – 40

Europe, Western Asia

2. The two main hypotheses that have been used to explain the origin and dispersal of modern humans :

3. Adaptive value of dark skin tones in equatorial regions such as Africa :

Melanin actually absorbs UV light. UV light can damage chromosomes and DNA so protection from UV is extremely important.Dark skin protects better against UV light. That extra protection isn't needed in colder, darker environments found at higher latitudes.

It may be that light skin evolved after agriculture when the diet no longer had enough vitamin D. Since there was insufficient vitamin D, those with light skin evolved since that would aid in vitamin D being created in the skin. Vitamin D is formed from UV light hitting certain chemicals. Obviously melanin would interfere with the creation of vitamin D.

Evolutionary pressure caused a lightening of skin tones away from this area :

As people moved to areas farther from the equator with lower UV levels, natural selection favored lighter skin which allowed UV rays to penetrate and produce essential vitamin D.

4. A woman’s diet during pregnancy have an impact on her future child and grandchildren :

A woman’s diet during pregnancy may affect the birthweight of her daughter’s children a generation later. Researchers discovered that the nutrition of a grandmother during her pregnancy can affect the size of her grandchildren at birth by influencing her daughter’s own physiology throughout her life because mother’s nutrition while she was in the womb herself and during her infancy play a greater role in the birth weight of her babies than what she eats as an adult or during pregnancy.

Research also said that the nutrition that a mother experienced when she was in utero has an intergenerational effect – influencing the nutrition that she provides to her own baby decades later. Mothers should be relaxed about their diet during pregnancy so long as it is balanced and healthy. It is proved that the mother’s body seems to do a good job of buffering overall nutritional supply to her growing baby. Within the bounds of a healthy balanced diet, the overall quantity of food that a mother eats is unlikely to have large effects on her baby’s birth weight.