ANTH 1013 1st Edition Lecture 17 Outline of Last Lecture I. HominoidsII. HumansOutline of Current Lecture I. HomininsII. How do we explain this constellation of features?III. Piltdown ManCurrent LectureI. Homininsi. Allopatric Speciationa. Lack of gene flow leads to divergence, accumulation of reproductive isolating mechanisms, and eventually speciationii. How would the earliest hominins have looked?a. What if there were cladogenic events during hominin evolution?b. Its entirely possible that there were many hominins that are not our ancestorsc. Can we find other hominin experiments?iii. Derived human traits:a. Obligately bipedalb. Small caninesc. Large brainsd. Broad dietary niche and tool usee. Extended time to maturityiv. In what order did human features evolve?a. This tells us what makes a hominin a homininb. Adaptively speaking, what set our lineage apart from the chimp lineage?c. How will we recognize the earliest hominin, keeping in mind that there is no requirement for “human” features to have evolved simultaneously as a package?v. Bipedalisma. Features related to bipedalism are found throughout the bodyb. Head: foramen magnum position and orientationc. Spine: curvature to redistribute weightThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.d. Pelvis and femur: reorienting center of gravity and changing actions of muscles1. Valgus knee: bicondylar angle2. Chimpanzee: narrow and tall ilium; ilium lies in coronal plane3. Human: broad and short ilium; ilium rotates into sagittal planee. Food: evenly distributing weight of entire body through entire footf. Cervical and lumbar lordosis1. There are 2 lordotic (posteriorly facing) curves in the human spine and kyphotic (anteriorly facing) curve2. In chimpanzees and other apes the spine is stiff and straight with a single slightly kyphotic (anteriorly facing) curveg. Bent hip, bent knee in chimpsh. Hip stabilizing mechanism1. The lesser gluteal muscles (gluteus medius and gluteus minimus) are hip extensors in other primates but are hip abductors or “stabilizers” in humans2. In humans, the iliac blade faces more laterally, which changes the orientation of the hip musclesi. Foot shape and function1. Chimpanzee: divergent hallux; weight distributed through entire foot2. Human: nondivergent hallux; weight distributed into arches of the footvi. Canines:a. Reduced height: humans have very small, nondimorphic caninesb. Loss of canine honing: extant nonhuman anthropoids have a functional complex that sharpens the canines and weaponizes themc. Loss of canine honing: the first mandibular premolar is “sectorial” in chimps.The human form is notvii. Increased brain sizea. Exceptionally larger than apes/chimpanzeesviii.Broad dietary niche and use of tools:a. Humans incorporate substantial quantities of meat protein in their diet in some environments and use tools to acquire food. Humans also have thick enamel on the postcanine teethix. Extended time to maturitya. We break the human lifetime into a series of milestones that are referred to as life historyb. Conception/pregnancy – 267 daysc. Infancy – period up to weaningd. All mammals are dependent on their mothers for food until they are weaned1. From birth to weaning, you are an infant2. When you are weaned, you lose dependency on mother for nutrition. You become a child3. Cross-culturally, in humans, natural period of nursing is about 3-4 years4. Human milk is low in fat and protein – frequent nursing5. Nursing suppresses ovulation – lactational amenorrheaa. Leads to average 4 year interbirth intervale. Even though you are weaned, you are still not capable of fending for yourselfwhen you are a child1. Humans provide food – unusual2. Brian development and social learning is important during childhood3. Community care important, paternal care increases4. Ends with the first eruption of your permanent teeth, specifically your first permanent molar (M1). This happens around 6 years of age in living humansa. The end of childhood also occurs at approximately the sametime as 95% of adult brain size is reachedf. As a juvenile, you continue to grow in size and engage in logs of socializationand learning1. Juvenility ends when the body is capable of reproduction (i.e., sexual maturity). You become an adolescenta. For females this milestone is menarche (first menstruation).b. For males this is the first ejaculation2. As a juvenile secondary sexual characteristics begin to develop: pubic hair, breasts, voice change, etc.g. Though capable of being a parent as an adolescent, the body does not ceasegrowth until later1. Between sexual maturity and physical maturity, you are adolescent2. Cultural recognition of adulthood occurs when you are physically matureh. Adulthood: get a job, work, eat, sleep, raise kids, get mocked by adolescents,become bitter, cynical, bald, etc.i. Senescence: aging of organ systems1. Menopause (early senescence of female reproductive organs)j. Life history evolves like any other trait. Human life history is different than that of a chimpanzee, our closest living relative1. Childhood and adolescence are unique to humansk. Humans have a unique life history: early weaning; offset of physical and sexual maturity; postmenopausal periodII. How do we explain this constellation of featuresi. ii. This model, developed before the human fossil record was known, predicts that big brains should have evolved firsta. In the past, it was common to portray human evolution as a ladder of progress, with some particular trends leading to modern humansiii. Early fossil discoveriesa. Engis, Belgium1. Neanderthal2. Discovered in 18293. Largely ignored until the 1900’sb. Gibraltar, Spain1. Neanderthal2. Discovered in 18483. Largely ignoredc. Neander valley1. Neanderthal type specimen – identified as a member of Homo neanderthalensis2. Feldhofer Grotto3. Discovered in 1856, described 1857d. La Chapelle aux Saints, France1. Discovered 19082. Neanderthal3. Elderly; missing postcanine teeth; elderly; missing postcanine teeth; alveoli resorbed; arthriticiv. Reactions to Neanderthalsa. Ernst Haeckel: Homo stupidus1. Marceline Boule: Brutish cave manb. People believed Neanderthals must have been a side branch of human evolution1. Neanderthals were found on continental Europe but not in England2. British scientists wanted human evolution to happen in their backyard, and