Read the proposed theories for the origins of bipedalism presented below. Select one theory that you find compelling and present two points of data in support of this theory. Select a second theory that you find improbable and present at least one point of data to counter this theory. Any information that you pull from a website you must cite (by including the web address next to the fact). Present your argument in essay format, using complete sentences. Do not simply copy and paste from other sources. Your total response should be no longer than 300 words in length.

ORIGINS OF BIPEDALISM

Why do we walk on two legs? If you asked a roomful of anthropologists, you'd likely not get the same answer from any two of them. Specialists cite everything from changing landscapes to needing to keep cool to heightening sexual attraction as probable causes of our upright stance, generally agreeing only on one point: everyone else's hypothesis is wrong. Think about the anatomical changes that accompanied bipedalism in light of the following theories. Do the theories hold up to inspection?

01 Hauling Food

As the African landscape shifted gradually from dense forests toward large patches of savannah, early hominids found their food supplies waning, leading them to descend from the trees and become ground-dwellers. Because these early human ancestors could no longer feed where they lived, they were forced to begin carrying large amounts of sustenance over long distances back to their home bases—a tricky task had they remained quadrupeds. While some anthropologists contend that early hominids gathered fruits and nuts, a few argue that they were scavengers, stealing predators' kills. An upright stance would have enabled our ancestors to lug carcasses to safer areas for consumption, while also allowing them to see other food sources or potential danger at greater distances.

02 A New World

Many anthropologists hypothesize that our ancestors developed an upright posture in order to carry food over long distances, but others believe they stood up merely to find it. As early hominids left the comfort of the forest to explore the savannah, they no longer needed a body structure suitable for climbing. Those who could walk upon two feet were better able to survive because they expended less energy and could travel longer distances than knuckle-walkers; they were also better able to see potential dangers lurking in the distance. Other anthropologists have suggested further environmental factors that might have helped urge our ancestors to stand upright, such as the cold and wet ground conditions that today lead chimpanzees to become temporary bipeds until they reach dry land.

03 Attracting Mates

Anthropologist C. Owen Lovejoy stirred controversy in 1981 when he attributed sex— specifically males' desire to get more of it—as a direct reason for why we walk upright. According to Lovejoy's behavioral model, males who could walk bipedally freed their arms to carry more food than their quadruped counterparts could hold, thus making the knucklewalkers seem far less appealing to females. In this model, the upright males were simply better breadwinners. Their ability to ration more food for females (who remained at the home base to care for the offspring) ensured that they were able to reproduce, thus leading to future generations of adept bipeds who in turn were able to pass on their own genes.

04 Grabbing a Bite

Some anthropologists argue that early hominids could not have become ground-dwellers and bipeds in a single evolutionary step, as many hypotheses imply. Instead, they contend, the ability to walk upright was in part a serendipitous by-product of new feeding habits. As our ancestors descended from the trees to forage on the ground for low-hanging fruits and berries, they began to feed from a squatting position. Over time, physiological changes occurred in their upper bodies, backbones, and pelvic areas, causing their weight and centers of balance to shift to a lower point in the body. This gave the hominids a steadier stance as well as the ability to stand upright with greater ease than their quadruped cousins. When our ancestors developed the need to reach higher and stand, these new physical traits came in handy—just as evolving a long neck proved favorable for the giraffe.

05 Keeping Cool

Walking on two feet did more than help early hominids conserve energy, as some hypotheses suggest—it also protected them from overheating. According to evolutionary biologist Peter Wheeler, early bipeds were generally exposed to less direct sunlight on the savannah than quadrupeds of the same size. In fact, when the sun shone directly overhead, the heat load upon a hominid on two feet would have been 60 percent less than that upon a knuckle-walker. Additionally, bipedalism raised hominids' bodies above the ground, enabling their skin to come in better contact with cooler and faster-moving breezes. This allowed for further heat dissipation through convection, and, says Wheeler, it meant that biped hominids needed to consume only about three pints of water per day, whereas quadrupeds needed five.

06 Aquatic Apes

Although most paleoanthropologists, despite their many differences, tend to agree that our ancestors became bipeds on dry land, a few suggest an alternate possibility. Aquatic Ape Theory, posed by marine biologist Alister Hardy in the 1930s, postulates that several human traits, from relatively minimal body hair to the ability to sweat moisture and salt, can be explained only through the idea that early hominids once lived in semi-aquatic environments. The hypothesis claims that our ancestors had to wade regularly through shallow lake- or riverside waters in order to reach shellfish, aquatic plants, and other potential food sources. With their heavy upper bodies, quadrupeds would have had a more difficult time adjusting to walking upright on the savannah than in buoyant water.

07 Weapons and Tools

Some of the oldest and most popular suggestions for why we developed into bipeds state that our upright posture relates directly to our need to use weapons and tools. While some researchers hypothesize that it was bipedalism that brought forth our ability to use these primitive devices, others believe the reverse—that the advent of tool and weapon use encouraged us to become bipedal. Charles Darwin, for one, felt that early hominids would have been "better able to defend themselves with stones or clubs, to attack their prey, or to otherwise obtain food" if they stood, walked, and ran erect, whereas quadrupeds of the same size would not have been able to exert the same force from a sitting or squatting position.

The following analysis of fuel by volume as per cent: H₂=50.4, CO=17, Ch₄=20, .C₄H₈=2, O₂=0.4, N₂=6.2, CO₂=4

(1)Product of CO₂% for dry analysis if 30% excess air

(2)Product of N₂% for dry analysis * if
30% excess air

(3)Product of O₂% for dry analysis * if 30%
excess air

(4)Product of H₂O% for wet analysis if 30% excess air

(5)The Stoichiometric A/F ratio by *
volume is

(6)Product of N₂% for wet analysis * if
30% excess air

(7)Product of O₂% for wet analysis * if 30% excess air

(8)Product of CO₂% for wet analysis if 30% excess air

Explain how the differing ages of rocks on the ocean's floor supports the theory of plate tectonics. In your answer, be sure to address the topics below.

A. Changes in the earth's magnetic field

B. Patterns of polarity in the seafloor

C. The thickness of sediments and the age of fossils in the seafloor

D. How this data supports the idea of seafloor spreading

Q43.

Enzymes are powerful catalysts, but are they affected by any factors? How would you study the rate of reaction (enzyme kinetics) in specific terms? What would you recommend to slow down the velocity of the enzymatic reaction in the presence of high concentration of substrate? In what way the reaction rate affected?

What are Malala's leadership qualities?

Folds are possible at which of the following 5 plate boundaries? More than one answer is possible!

Group of answer choices

A. C-C Divergent

B.O-C Convergent

C. O-O Transform

D. O-O convergent

E. C-C Convergent

The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599 among smokers. The prevalence of smoking in the population is 55%. Among smokers, the etiologic fraction of disease due to smoking is:

A.

cannot be determined from the information provided.

B.

0.90 for lung cancer and 0.88 for coronary thrombosis.

C.

0.90 for lung cancer and 0.29 for coronary thrombosis.

D.

0.89 for lung cancer and 0.88 for coronary thrombosis.

E.

0.89 for lung cancer and 0.29 for coronary thrombosis.

CO(g)+H20(g) <---> CO2(g)+H2(g) delta h =-9

Use le chateliers principal to predict the effects on the equilibrium

CO2 added

Temp increased

Pressure increased

Catalyst removed

H2o removed

what is the difference between selenderness ratio in horizontal and vertical separator ?

Discuss with the aid of diagrams any three (3) particle size reduction equipment?

Given the observed longwave radiation (incoming and outgoing) and the observed shortwave radiation (incoming and outgoing) how would you calculate the observed albedo?

A cross-country pipeline transports crude oil at a rate of 500,000 barrels per day. The pressure of the oil leaving Pumping Station A is 500 psig. The pressure at the inlet of Pumping Station B is 75 psig. Station B is at an elevation 157 feet higher than Station A. Given the crude oil density is 48.0 lbm/ft3 and one barrel is equivalent to 42 gallons, determine (a) the work loss (ft∙lbf /lbm) between A and B and (b) the equivalent power consumed in the process (horsepower).

Fluid Mechanics

A vapor mixture of -butane (B) and -heptane (H) contains 40.0 mole% butane at 80°C enters a condenser at a rate 4 kg/s. Liquid and vapor product streams emerge from the process in equilibrium at 40◦C. The vapor product has a 45.0 mole% butane composition. Determine: a. The pressure in the condenser b. The composition and flowrate (mol/s) of the liquid stream c. During operation, the system contains a 3m depth of the liquid phase (S.G. = 1.41) at any given time. If the maximum pressure the vessel floor joints can handle is 1 bar, will the tank rupture?

1) 10000 lb/h of a 40.00% NaoH solution is crystallized through a combined evaporator-crystallizer process. The feed enters an evaporator which concentrates it to 50.00% NaOH. The concentrated solution then enters the crystallizer with a built in filter. The crystal product is 95% NaOH crystals with the remaining 5% as adhering mother liquor solution. The mother liquor, containing 45.00% NaOH, is mixed back to the feed before entering the evaporator. Determine the recycle flow rate.

2) Resolve the problem, now considering if the mother liquor is not recycled, but the entire process still generates the same amount of product (crystals) as the original problem. Retain all concentrations given. Determine the amount of feed needed if the recycle stream was removed. Compare the recovery ratio (lb NaOH recovered as crystals/lb NaOH in feed) for the two cases to see the importance of the recycle stream.

Questions:

1. The densities of ice and water at 0 °C are 0.9168 and 0.9998 g cm–3,respectively. If ∆H for the fusion process at atmospheric pressure is 6.025 kJmol–1,

   1. What is ∆U?

   2. How much work is done on the system?

2. For each of the following processes, state which of the quantities ∆U, ∆H, and ∆S are equal to zero. Explain with logical reasoning.

   1. Isothermal reversible expansion of an ideal gas.

   2. Adiabatic expansion of an ideal gas through a throttling valve.

   3. Vaporization of liquid water at 80 °C and 1 bar pressure.

   4. Reaction between H2SO4 and NaOH in dilute aqueous solution at constant temperature and pressure.