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NYU / Engineering / ANTH 2 / What is Hominin?

What is Hominin?

What is Hominin?


Anthropology: the study of the evolution and culture of humans and other primates. Subfields are  biological, sociocultural, linguistics, and archaeology.

What is Hominin?

• Primate: member of mammalian order; primates defined by series of traits (all shared) • Hominin: member of our (direct) lineage—humans and their fossil ancestors after their  evolutionary split from apes

• Hominid: humans and great apes

• Evolution: change in the frequency of a gene or trait over generations (descent with  modification)

• Culture: the sum total of a group’s learned traditions

• Biological anthropology: study of evolution as it relates to human species, diversity, or indirectly o Osteology: study of skeletal biology

o Paleoanthropology: study of fossil record of ancestral humans and primate relatives o Bio archaeology: study of human remains in archaeological context

o Forensic anthropology: study of human remains applied to a legal context

o Primatology: study of living, non-human primates and anatomy, genetics, behavior, and  ecology

What is Hominid?

We also discuss several other topics like what is classical condition?

o Human biology: study of human growth and development, adaptation and variation,  nutrition

o Molecular anthropology: study of genetics in humans and non-human primates • Sociocultural anthropology; study of human societies in cross-cultural perspective o Theory

▪ Ethnology: the comparison of ethnographies (cross-cultural)

▪ Ethnography: description of customs of individual people or cultures

o Study topics: colonialism, nationalism, gender and sexuality, feminism, religion, politics  and law, media, etc.

• Linguistic anthropology: study of language; its origin and use

• Archaeology: study of material culture of past peoples

o Artifacts: the objects; from tools to art, left by earlier groups of people If you want to learn more check out What is Peer review?

o Historical: written records and traditions and prehistorical archaeology

Vertebrates: animals with a backbone; Tetrapods: vertebrates with limbs; Amniotes: tetrapods with  an amniotic egg (amnion).  

What is Evolution?

Incomplete list of shared derived traits to know for the exam: If you want to learn more check out What header file must you #include if you are going to use file input or output in your program?

o Mammals:

o Mammary glands (not all mammals have nipples) We also discuss several other topics like What are features of the International Gothic style?

o Hair (all mammals have hair)

o Heterodonty (differentiation of teeth)


o All primates derived traits:

o Nails

o Grasping hands and feet

o Derived traits:

o 1st digit opposability  

▪ Pollex on hand

▪ Hallux on foot (not humans)

o Convergent orbits and postorbital bar or closure  

o Reduced snout and olfactory bulb

o Increase in overall brain size.

1st major division of primates: Lemurs and lorises

o Strepsirrhines (wet noses)  

o Grooming/toilet claw (hind limb)

o Tooth comb: 4 teeth at lower jaw for grooming

2nd major division of primates: Tarsiers and anthropoids  

1. Tarsiers

o Nocturnal

o Haplorrhines (dry nose)

o Loss or rhinarium

o Increased postorbital closure (partial closure in tarsiers)

o Because they have no eye shine, they have big eyeballs Don't forget about the age old question of Q: What causes day and night?

2. Anthropoids

o Closed orbit (complete postorbital closure)

o Further increase in brain size.

o Old World monkeys and apes  

o Catarrhines: loss of a premolar  

▪ Dental formula: If you want to learn more check out How does this relate to bioavailability?

▪ Cercopithecoids: tall, crested (bilophodont) molars [vs. hominoids, which have  simple, rounded molars]

o Apes and/including humans (hominoids):  

▪ Loss of tail

▪ Upright body plan  

• Mobile shoulder

• Wrist joints

• Long arms

• Short trunk/torso.

Summary of primate biogeography 

• Lemurs: Madagascar

• Lorises: Mainland African and SE Asia

• Tarsiers: SE Asia

• New World monkeys: Central & South America

• Old World monkeys: Africa and Eurasia

• Nonhuman apes:  

o Gibbons and orangutans: SE Asia

o Gorillas, chimpanzees, bonobos: Africa

Mating systems


• Pair-bonded groups (male, female, dependent offspring)

o Lifetime monogamy: mating pairs are stable over lifetime

o Sexual monogamy: mating pairs are stable over breeding season

o Relatively rare in mammals (less than 59%; common in birds, more than 90%) • Primate example:

o Gibbons


• Polygamy: any mating system that’s not monogamy

o 1 male, multi-female

o Most common mammalian patterns

o 2 main types in primates:

▪ Female defined polygyny: males guard cluster of females (“harem”) • Primate example: gorillas

▪ Dispersed mating (solitary)

• Can be polygynandry

• Primate example: orangutans


• 1 female, mutli-male

• Primate example:

o Some marmosets and tamarins

o Facultative polyandry

o Related to twinning?


• Mutli-male/multi-female

• Promiscuous mating (loaded term)

• Primate example:

o Chimps and bonobos

o Macaques

Primate diets: most primates are generalists; diet affects day/home range

• Fruit (Frugivory)

o Patchy distribution in time and space (some trees =fruit, some don’t; depends on  season)

o Easy to digest

o High carbs, low protein

• Seeds (Gramnivory)

o Tougher to process

• Flowers/nectar (Nectivory)

o Like fruit, patchy in time and space (similar to fruit)

• Leaves and stems (Folivory)

o High protein, low carbs

o Abundant (more than fruit) but harder to digest

• Exudates—gum and sap (Gumnivory)

o Requires specialized feeding adaptations (tusk-like incisors)

• Tubers, roots, bulbs, etc.

o Important for savannas

o Requires work to acquire and ingest (dig; difficult to digest)

• Animal matter (Faunivory)

o Includes invertebrates and vertebrates

o Good source of energy but hard to catch  

• Other

o Grass (grass seeds)

▪ Geladas

o Bark

▪ Orangutans

Body size and diet:  

• Larger animals????absolutely more food, relatively less energy, lower quality foods (leaves) • Small animals????absolutely less food, relatively more energy, higher quality foods (e.g., insects)

Primate biomes and environments

Tropical biomes

• Majority of primate species

• Largely defined by latitude (near equator)

Tropical rainforest

• Defined by latitude and rainfall

• No water and summer—just rainy seasons

• Always some trees fruiting all year round

Tropical seasonal forests

• More variable rainfall throughout year

• Some trees will lose leaves

• Less extensive canopy

Other tropical biomes occupied by primates

• Savanna

o Grasslands with some trees/shrubs

o Primates only found in African savannas

• Woodlands, thorn woods, shrub lands

o Areas between forest and savanna

• Habitats based on water

o Coastal

o Mangrove

o Swamp

o Riverine

• Bamboo forests

Temperate biomes

• Very few genera found outside tropics

o Some macaques: Japanese snow monkeys and Barbary macaques o Some leaf-eating monkeys

Why are primates social? Why live in groups?

• Anti-predation strategies

o Increased vigilance (awareness)

o Cooperative defense

▪ “mobbing” (group defense)

o Alarm calls  

o Dilution effect (so many; predator’s confused and can’t focus on one) o “selfish herd” (healthy animals protected; leave older, or young, animals) o predator confusion

• Foraging: finding and accessing food

o More eyes to find food

o More efficient foraging

o Competition for resources

▪ Defense of takeover of food patches/territory

▪ Cooperation in hunting

o Limited resources

▪ More resources necessary

▪ more competition over resources

▪ more conspicuousness to prey

▪ more territory for nesting sites, food, water, etc.

• Social interaction

o Access to mates

o Assistance in child-rearing

o More learning opportunities

o Information sharing

o Cooperation/coalitions

o Presence of males = protection form predators

o Costs: social conflicts and disease

▪ High risk of disease

▪ Social conflicts

▪ Competition for mates

▪ Aggression

▪ Presence of males = infanticide

• Infanticide = highest cause of infant mortality in mountain gorillas

Phylogeny (a hypothesis of evolutionary relationships) vs. taxonomy (the classification system used)

o Phylogeny = hypothesis because information is always changing

o Taxonomy = best when reflects phylogeny

Catastrophism (one or more disasters created features on the earth in a short time) vs.  Uniformitarianism (geological processes acting today were acting in the past; the earth is ancient)

o Catastrophism: relatives in different climates experienced biological changes due to new  environments

o Extinction as evidence for catastrophic disasters that wiped out past life forms; new  creations/migrations replaced them

o No framework for mechanism of change

o American degeneracy (WRONG)

▪ Animals in the Americas degenerate into lesser forms

o Uniformitarianism: geological processes are uniform over time; slow, gradual changes suggest  ancient age of Earth

o Lyell’s Principles of Geology: major evolutionary influence

Typology and essentialism (the Greeks) vs. population thinking (i.e., emphasis on variation – Darwin)

• Plato and Aristotle’s essentialism

o Early attempt at understanding and ordering the natural world

▪ The eidos (idea or type) is the only thing that is fixed and real

o Gaps in nature are real and represent discontinuities between types

▪ Immutability of species: an unalterable fixity of essence

• Typological thinking and the great chain of being

o Scala naturae: the great chain of being

▪ Life arranged in orderly, hierarchical order

▪ Humans at the top, various groups below:

• Beasts (mammals)

• Birds

• Fish

• Reptiles

• Insects

• Plants

• Minerals

• Carl von Linne, Systema Naturae (book)

o Orders primates; first time humans are with mammalian order

▪ Humans in Hominidae; great apes in Pongidae

▪ Binomial nomenclature; genus and species

Inheritance of acquired characteristics (Lamarck) vs. natural selection (Darwin) and particulate  inheritance (aka Genetics – Mendel)

• Jean-Baptiste Lamarck

o Change in individual’s lifetime through use or disuse

o Acquired or lost traits are passed to next generation = WRONG

▪ Ex: giraffes with longer necks

• Evolution by natural selection:

o Lamarck’s theory: variation is acquired

o Darwin’s theory: variation is inherited

o Variation is the key

o Differential survival and reproduction

• Gregor Mendel

o Demonstrated particulate inheritance: the concept of heredity based on transmission of  genes

▪ Common garden peas—dichotomous variation; independent traits are bred  true—produce strains of plants that resembled their parents’ generation after  generation

Homology (a trait shared from common descent) vs. Homoplasy (convergent or independent  evolution)

• Homology: similarity of traits resulting from shared ancestry, a result of descent with  modification

o Ex: humans are similar to birds

o Different from each other but with similar base

• Convergence (analogy, homoplasy); appearance of similar traits due to similar use, not common  ancestry

o Wings in insects, birds, bats

o Warm-bloodedness (endothermy) in birds and mammals

o In contrast to homology

“Ontogeny” does not “recapitulate phylogeny” – development proceeds from general to specific

• Ernst Haeckel (1834-1919)

o Ontogeny recapitulates phylogeny: independent development retraces the evolutionary  history of a species (ex: fish, amphibian stages)

o Ontogeny: growth and development

▪ Ex: see embryo pass through different evolutionary stages =  


• Karl Ernst von Baer (1792-1876)

o Primary germ layers; all organism made with same tissues

o Von Baer’s law of development proceeds from general to specific

Steroid hormones: androgens, estrogens, gonad and genital formation, secondary sexual  characteristics

Steroid hormones

• Gonads (ovaries or testes) create androgens

• Androgens can then be converted into estrogens

• Estrogens and androgens are present in males and females at different concentrations • Androgen

o Converted from progestin in gonads

o Testosterone in primary androgen

o Necessary for penis formation and spermatogenesis (sperm creation)

o Influence male secondary sexual characteristics—pattern and density of body hair;  comb size in roosters; antler growth in deer, etc.  

o Behavior effects—mating, aggression, etc.  

• Estrogen

o Converted from androgen in gonads

o If excess androgens are produced and not immediately converted to estrogen, they can  affect female physiology and behavior

o Influence genital tract formation (ex: uterus size)

o Influence female secondary sexual characteristics (ex: breasts)

o Influence sexual behavior and maternal aggression

Why chromosomes don’t necessarily determine sex (and certainly not sexuality or gender). Think  androgen insensitivity, adrenal hyperplasia, and XO, XXY, and other nondisjunction errors

• Complete androgen insensitivity syndrome

o XY but inability to respond to androgen

o Manifests in undescended testicles and “feminized” genitalia

o Intersex

• Congenital adrenal hyperplasia

o XX with oversized, overactive adrenal glands

o Can result in male sexual characteristics (external genitalia, facial hair, etc.) • 5-alpha-reductase deficiency (testes descend at age 12)

• sex-chromosome variants:

o XO (Turner’s syndrome): only 1 sex chromosome

o XXY (Kleinfelter’s syndrome): trisomy of sex chromosomes


Adaptive radiation and island biogeography – e.g., Galapagos tortoises and finches

• Adaptive radiation: diversification from one founding species into man species occupying  different niches  

o Galapagos Finches:  

▪ Beak differences

• Cactus finch: long beak

• Ground finch; short beak

• Tree finch: parrot-shaped beak for stripping

o Galapagos tortoises

▪ Giant tortoises vary in shell shapes

• Dome-shaped on lush islands

• Saddle-shaped on arid islands

Artificial selection as a special type of natural selection in which humans select which plants or  animals reproduce

• Artificial selection: process by which humans select which member of a species reproduce o Farmers select for certain features in plants (seeds, stems, leaves, fruit)

o Animal breeders select for woolier coats, milk or meat production, etc.

• Natural selection but humans are doing it

Preformationism vs. blending inheritance vs. epigenesist (formation of a zygote – fertilized egg)

• Preformationism: WRONG

o Tiny version of fully formed individual in sex cells (homunculus)

o Problems:

1. Infinite homunculi

2. Hybrid domestic animals

o Eventually replaced by the concept of epigenesist: an organism develops from a  fertilized egg

• Darwin’s blending inheritance: uniform blend or parents’ phenotypes (outward appearance) are  passed on to offspring  

o Problem: fitness effects of 1 parent would be blended out by the other parent; this  diminishment continues with offspring  

o Variation can’t be maintained in this way

DNA replication, transcription, translation, protein synthesis, mitosis, meiosis

• DNA replication

o Occurs during cell division

o Enzyme separates bonds—DNA is “unzipped”

o Assembly of complementary nucleotides

o 1 parent DNA strand into 2 daughter strands

• Protein synthesis: assembly of proteins from amino acids, which occur at ribosomes in  cytoplasm via mRNA

A. Transciption (in nucleus)

1. DNA unzips

2. RNA strand forms and copies DNA

3. mRNA leaves nucleus and goes to ribosome

B. Translation (in ribosome)

       1. mRNA binds to ribosome

       2. ribosome reads codon 1 by 1

       3. tRNA brings coded for amino acid for each codon

a. Protein chain formed

• Mitosis: somatic cell division that results in formation of 2 daughter cells; 1 diploid cell to 2  diploid cells

• Meiosis: sex cell division in testes and ovaries; results in genetically distinct gametes; 1 diploid  cell to 4 haploid cells


• Locus: location of a gene on chromosome

• Allele: variant form of a gene

o Homozygous: same allele at both loci of gene

o Heterozygous: 2 different alleles at loci of gene

• Dominant: allele always expressed when present

• Recessive: masked allele when dominant allele is present  

• Codominant: the alleles are co-expressed; neither is dominant

o Ex: ABO blood system  

• Punnett square


Forces of evolution

• Gene flow: exchange of genetic material between populations (admixture) o Migration with reproduction

o High genetic relatedness between populations

o Introduce new genotypes and phenotypes to populations

o High variation within, low variation between

▪ Populations within a species (generally)

• Mutation: errors during DNA replication = random alterations in DNA sequence o Mutations in non-coding regions are neutral

o Mutations in coding regions are neutral or good/bad

o Mutations in gametes are passed on

o Ultimate source of novel genetic variation


• Genetic drift: random changes in gene frequencies in population due to random sampling;  neutral theory

o Effect inversely proportional to population size; strongest in small population o Effect often greater over longer time periods

o Random: no directionality

o Fixation or disappearance of alleles

▪ Can’t affect population quickly

o Ex: Bottleneck: dramatic drop in population size

▪ Results in low genetic variation

▪ Long, slow process of mutation accumulation to rebuild genetic diversity

▪ Disease threat (anti-disease resistance)

o Ex: Founder effect: new populations that become isolated from their parent population  and carry a subset of genetic variation

• Natural selection: differential survival and reproduction

o Acts on phenotype, not genotype

o Directional selection: selection against 1 extreme

o Stabilizing selection: selection against both extremes (or average)

• Genetic drift and natural selection

o Drift: strongest in small populations over long time periods

o Selection: can be strong in large populations over short time periods

▪ Ex: stabilizing selection: 7 vertebrae in mammals

Darwin’s theory of evolution + Mendel’s theory of inheritance = Evolutionary synthesis

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