Guided Response: Review several of your peers' posts that contain a hypothesis different from your own and compare findings. Respond to at least two of your peers and provide recommendations to extend their thinking.

Challenge your peers by asking a question that may cause them to reevaluate elements of their hypothesis. Each response should be at least 50 words in length.

Brooke

I think the Upright Scavenger hypothesis by anthropologist Pat Shipman makes the most sense for why bipedalism first evolved. This hypothesis is based on evidence Shipman found showing that locations where hominids lived had traces of bones they retrieved from hunting. "Walking on two feet was likely advantageous to hominids who were opportunistic scavengers.

Scavengers need to find their quarry, and that means walking great distances and scanning a broad territory for evidence of a predator kill. Bipedalism is highly energy-efficient, in part because it involves only two limbs and yield greater endurance for walking long distances" (Feder, 2013, p. 87).

Walking on two feet would have made getting in and out of situations, where a prey might be, a lot faster than if they had to use all four limbs. Also, "The free hands of a bipedal hominid can carry both the tools for extracting the meat from the carcass and the meat" (Feder, 2013, p. 87).

I think this is the most convincing hypothesis because humans could travel long distances and hunt for food more efficiently than if they were quadrupedal.

According to the textbook, "Hominids seem uniquely adapted for long-distance running, and this ability to cover great distances may have been highly advantageous" (Feder, 2013, p. 94). I think the hypothesis by Pat Shipman makes the most sense because it seems to fall between The Upright Provider hypothesis by Owen Lovejoy and The Efficient Walker hypothesis by Peter Rodman and Henry McHenry.

Shipman's hypothesis combines the idea that hominids became bipedal so that they could travel great distances more efficiently while using their hands to scavenge and gather food for their families.

Reference

Feder, K. L. (2013). The past in perspective: An introduction to human prehistory (6th ed.). New York, NY: Oxford University Press.

LaTesa

Week 1 Bipedalism Hypothesis

Because I believe the theory behind bipedalism is taking the track of proving natural selection and the evolutionary concept. I find Owen Lovejoy's hypothesis preposterous. It gives too much "sensibility" to otherwise simple primates.

I think any animal can be taught certain actions, but I don't believe they can be taught to consider their young if that isn't already an innate ability.

I also refuse the efficient walker hypothesis of Rodman and McHenry. This theory is nonsensical as nature would have had to decide that quadrupedalism in chimps was a bad idea because they used too much energy to accomplish certain tasks.

The endurance runner theory of Bramble and Lieberman is not my choice either. I'll use Feder's words to explain why. He said "Bipedal running can be an unsteady way of moving about, and here too humans seem uniquely well adapted to maintain stability, especially with a pelvic configuration that allows for large and powerful gluteal muscles that work to keep us upright (2013).

This leaves Shipman's upright scavenger as the one to best explain why bipedalism first evolved. It would seem to follow that if humans evolved from apes, made it through the process of natural selection as Darwin explains it, that the upright scavenger hypothesis provides the reasoning for evolving from quadrupedalism to bipedalism.

Feder, K. L. (2013). The past in perspective: An introduction to human prehistory (6th ed.).

New York, Oxford University Press.