Conceptual questions and answers quiz 2

Does biological variation among humans mean that biological races exist?

No. Humans possess biological variation, but it occurs mainly as overlapping, gradual clines rather than discrete groups. Human populations have not been isolated enough to form biological races, although race remains socially and culturally real.

What does very low human genetic diversity reveal about race?

Continental human populations are genetically very similar. Even some neighboring chimpanzee populations are more differentiated.

• This contradicts the idea that human consist of deeply separate biological races.

How did early human dispersals shape present-day genetic variation?

As small groups moved away from Africa, repeated founder effects meant that each migrating group carried only part of the previous population’s variation.

• This produced geographic patterns of ancestry without creating discrete races

Why can genetic clusters or visible differences not be treated as proof of biological race?

Clusters depend partly on sampling and reflect ancestry, geography, migration, and gene flow. Visible traits may reflect particular local adaptations, but they do not divide the entire genome into matching racial packages

• ex: USA

Why is biological determinism an inadequate explanation for human differences?

Most traits develop through interactions among many genes, environments, development, culture, and inherited social conditions; so heritability within a population also cannot establish that differences between group averages are genetic.

How does acclimatization differ from evolutionary adaptation?

Acclimatization is a reversible response within an individual’s lifetime, such as tanning or increased hemoglobin at high altitude. Evolutionary adaptation is a heritable population-level change developing across generations, such as skin color.

Why should human evolution be studied beyond the explanation of adaptation?

Not every difference is an adaptation. Human variation reflects natural selection, genetic drift, mutation, migration, and hybridization, while some traits change indirectly because they are correlated with other traits.

What major characteristics distinguish primates from many other mammals?

Primates generally possess grasping hands and feet, usually nails reather than claws, steroscopic vision, relatively large and complex brains, and relatively long lifespans

How do main theories of primate orgins differ

• Arboreal theory emphasizes adaptation to life in trees

• Visual predation theory emphasizes catching insect prey

• Terminal branch feeding theory emphasizes gathering fruits, flowers, and nectar from small branches.

So basically, they differ as they look at the different usages of the features primates have.

Why is phyletic classification more informative than dividing primates into prosimians and anthropoids?

• “Prosimians” groups animals by primitive resemblance rather than shared derived traits

• Phyletic classification shows that tarsiers share a more recent evolutionary relationship with monkeys and apes as haplorhines'

It’s not specific enough, basically

What broad characteristics and distribution patterns define strepsirrhines?

Strepsirrhines retain many ancestral mammalian traits but also possess derived features such as a tooth comb. Most are small and nocturnal and do not form large groups. Lemurs live in Madagascar, while lorises and galagos live in Africa and Asia.

How do the aye-aye and sifaka illustrate strepsirrhine diversity?

• The nocturnal aye-aye uses large incisors and a slender finger to obtain concealed foods.

• Sifakas have long hindlimbs adapted for vertical clinging and leaping.

Why are Madagascar’s lemurs considered an adaptive radiation?

Geographic isolation allowed one ancestral lineage to diversify into species with different diets, activity patterns, locomotor adaptations, and social systems without competition from monkeys and apes.

Galagos and lorises similiarities and differences

• Both are generally small, nocturnal, and arboreal

• But galagos are primarily rapid leapers with elongated hindlimbs and ankles, while lorises use powerful grasping limbs for slow, controlled climbing

How do the dental formulas of apes, typical New World monkeys, and marmosets/tamarins differ?

• Apes: 2.1.2.3 = 32 teeth in total

• New World monkeys: 2.1.3.3 = 36 teeth in total

• Marmosets and tamarins: 2.1.3.2 = 32 in total

What broadly distinguishes platyrrhines from Catarrhines?

Platyrrhines are the new world monkeys of central and south america. They generally have:

• broad outward-facing nostrils

• and 3 pre-molars rather than 2.

The key differences among the three major platyrrhine families

• Pitheciids: include titis and seed-specialized sakis and uakaris.

• Ateliers: the largest new world monkeys and have long prehensile tails used in climbing and suspension.

• Cebids: are highly diverse and include omnivorous capuchins and squirrel monkeys, noctunal owl monkeys and very small callitrichines (some type of monkey)

Which representative New World Monkeys best illustrate distinctive adaptations?

You can look at it by monkeys distincted adaptations:

• Howler monkeys are major leaf eaters with powerful calls

• spider monkeys are suspensory ripe-fruit eaters with fission-fusion societies

• capuchins are dexterous omnivores, with some using tools

• Aotus is the only nocturnal higher primate

• marmosets use chisel-like incisors to obtain tree exudates.

How are callitrichine feeding, locomotion, and reproduction connected?

Marmosets and tamarins are very small monkeys with claw-like digits that help them cling to trunks while feeding on insects and exudates. They commonly produce twins, and fathers and other group members help carry and care for the infants. These traits form a linked adaptation to small body size, energetic foods, and high infant-care demands.