CH 17

patchy and seasonal more energy and nutrients directional more sophisticated toolmaking and hunting Homo sapiens ecological rather than social

A change in habitat from rainforest to woody grassland, making food _________________ may have been a selective pressure favoring larger brains in early hominins. Larger brains require _____________________, and selection favored adaptations that helped provide them, such as an upright posture and using tools to dig and butcher. During the Pleistocene glaciations, selection favored adaptations for survival in harsh, variable environments, and _____________ selection for larger brains became more frequent in the Homo genus than it had been in Australopithecines. Larger brains provided more selective pressure, and ____________________ first appeared in the Homo genus. Indications of complex language use, such as ceremonial art, trade over long distances, an local experimentation with tool design, appeared only after brains reached the size of _______________. Computer modeling suggests that the strongest selective pressures driving the evolution of intelligence in hominins have likely been __________________ interactions, highlighting the value of skills such as tool making and use.

Homo neanderthalensis: - muscular build - long, low skull - wide shoulders - prominent brow ridge - wide nose Homo sapiens: - narrow shoulders - flat face - slender build

Categorize the following anatomical features as belonging to Homo neanderthalensis or H. sapiens.

- oxytocin - dopamine - a combination of oxytocin and vasopressin - dopamine

Choose the hormone trigger that is primarily responsible for producing the physiological and emotional responses in each scenario. - A human mother picks up her newborn baby, who is crying in distress. As she comforts the baby, she strengthens the bond between mother and child. oxytocin - A foraging deer smells a patch of cabbage. She raises her head and dilates her nostrils, moving toward the odor. When she locates the patch, she begins eating. dopamine - A male and female prairie vole find each other, and after mutual inspection they mate and develop a monogamous relationship. - A woman out fly fishing sees a fish pursue her fly. She tenses at the sight and watches her line intently as she waits for the fish to strike her fly.

Anatomical similarities: - bipedalism - upper body straight above hips - walking with heel first - vertically oriented foramen magnum Anatomical differences: - brain size - body size and shape - digit length and shape - adaptations for tree climbing

Compare and contrast the anatomy of australopithecines and Homo by sorting the traits that are anatomically similar or anatomically different between them.

- Scientists are studying the evolution‑based relationship between brain chemistry and emotions.

How can an understanding of evolution help us to better understand psychiatric disorders? - Psychiatric disorders are caused by random mutations and cannot be understood by studying evolution. - Scientists are studying the fossil record of early hominids for evidence of psychiatric disorders. - Scientists are studying the evolution‑based relationship between brain chemistry and emotions. - Scientists are studying the effect of trauma on psychiatric disorders.

- Levallois - Oldowan - Acheulean

Identify the description of each type of tool as an Oldowan, Acheulean, or Levallois tool. - This type of tool is approximately 400,000 years old and is made from stone. It is a sophisticated broad, flat blade that is very sharp and could have been used for cutting and scraping by Homo heidelbergensis. - This type of tool is approximately 2.6 million years old and was discovered in Tanzania. It is a primitive tool made from stone and appears to have been used for crushing. - This type of tool is approximately 1 million years old and is a hand axe made from stone. Tools similar to this one have been found in Africa, Asia, and Europe in conjunction with Homo erectus fossils.

South Africa Homo independent evolution hybridization

In 2013, 15 nearly complete fossilized skeletons of Homo naledi were discovered in ______________. When these fossils were analyzed, some scientists hypothesized that H. naledi split from other hominins in the _______ lineage very early on. Early divergence in Homo history suggests that H. naledi may have evolved some human‑like traits through ____________________. Because H. naledi and H. sapiens lived around the same time, human‑like features in H. naledi may also have been due to ______________ between primitive and derived hominins.

the changing environment drier grasslands forage stay cooler

Most scientists agree that ______________________ was the driver for the evolution of bipedalism in early hominins. Toward the end of the Miocene, as the climate became _________, dense African forests changed to _____________. One hypothesis of bipedalism suggests that bipedalism allowed hominins to _________ more efficiently. Because trees were more scattered, early hominins could save energy by walking from tree to tree and reaching for food instead of climbing trees. Another hypothesis of bipedalism suggests that walking erect allowed hominins to _______________ when moving in open habitats such as grasslands. By walking upright, they were able to reduce the amount of surface area being exposed to the sun

how other primates communicate with each other investigating genetic disorders affecting language the genes influencing conducting phylogenetic studies to map brain evolution have less genetic capacity

No other species uses language the way humans do. Scientists infer that language is adaptive, and they take several approaches to studying it. For example, studying ______________________ may provide insight into the evolutionary precursors of human language. Another approach is to identify the underlying basis of human language by __________________ and studying __________________ language production. Yet another way to tackle the problem is to investigate how the brain's ability to manipulate language has changed over time by _____________________________. Two of these lines of research are similar in that they identify steps in language evolution, and in all of them researchers compare a group that produces standard human language to groups that ______________________ for language.

bipedalism use primitive stone tools a large brain

Scientists hypothesize that the first major adaptation that led to the evolution of modern humans was the evolution of ______________. It led to the first major divergence of the hominin lineage from bonobos. Later, australopithecines fossils were first to show that hominins had developed the ability to ______________________. The most recent physical adaptation that set the Homo sapiens lineage apart from its ancestors was ________________.

- Humans and primates share a monophyletic clade as evidenced by DNA analysis. - Humans and primates share homologies, such as between the human coccyx and primate tails.

Select the statements that describe evidence used to classify humans as primates.

Indonesia Homo erectus shorter smaller Homo habilis 2 million

There are two hypotheses regarding the origin of a hominin species found in ___________ called Homo floresiensis. One hypothesis states that H. floresiensis evolved from _____________ because fossils of both species were found on Indonesian islands dating to the same time period. One major problem with this hypothesis is that H. floresiensis was much _________ and had a __________ braincase than the other hominin. Scientists cannot say for certain that both hominin species were closely related because of additional physical differences. Another hypothesis states that Homo floresiensis was a descendant of _______________. These two species had a similar body structure. This hypothesis means that this predecessor would have migrated out of Africa around ____________ years ago.

DNA a molecular phylogeny morphological evidence

To be able to trace the evolutionary history of Neanderthals and Homo sapiens using genetic evidence, scientists must first retrieve _____ from fossils. Once sequenced, this genetic information can be used to produce ___________________ comparing the evolutionary ancestry of the two groups. The final step scientists take is to compare the genetic evidence to ___________________ to determine if the two sets of data agree.

- Living apes use simple tools such as twigs, stones, and leaves. - The Homo habilis lineage is younger than 3.3 million years old. - Scientists have found stone tools dating to 3.3 million years ago.

What evidence refutes the idea that Homo habilis was the first "Handy Man"?

- Two lizard species sometimes interbreed successfully, exchanging alleles between the species.

Which scenario describes the process of introgression?

- menopause at an older age - having children at an earlier age - short body height - low blood pressure

Which traits are favored by natural selection to increase reproductive success in modern‑day women?

- Homoplasies among hominin lineages can make a hominin fossil appear to be closely related to several known species.

Why does homoplasy in hominins make it challenging to categorize hominin fossils?

- Toolmaking provided better access to food sources.

Why was toolmaking an important evolutionary development for hominins?