Question

Why would natural selection select for changes from quadrupedalism toward more efficient bipedalism and What advantages are there to being efficiently bipedal in early hominins? Consider environment, energy expenditure (in the form of calories) and biocultural evolution in your response.

Answer 1

Natural selection is a very important mechanism of evolution. It involves changes in the heritable traits or characteristics of a population which then is passed on over generations.

It is a known fact that human have evolved from a creature with quadrupedalism to bipedalism. This has happened over a course of many years and is infact an outcome of natural selection . Natural selection on its own cannot create a behavior like that of bipedalism, but it can function in  selecting the behavior once it has arisen. Some early hominids were surely better at upright walking than others, as this behaviour permitted them to forage widely and has given many other advantages, they adopted this way of walking and with generation this trait passed on to the future humanoids.

Bipedalism brought with it a host of advantages. It would allow males to fetch high-quality food for their mates and offsprings, this trait also helped protect them from looming dangers due to the added flexibility. Bipedalism allowed hominids to free their arms completely, thus enabling them to use tools efficiently, they could stretch to pluck fruit from trees using the free hands . They could also use hands for socialising and communication.

One more important benefit of a biped was that their bodies were less exposed to sunlight while standing upright. Also the energy utilisation was less while walking on two legs than on four legs.  Recent studies have shown that a biped uses 25% less energy while walking than a quadruped. This energy saving quality gave the early hominids more energy to reproduce and thus giving more chance of producing offspring with this unique trait . Also during droughts , harsh environment, food scarcity etc the concerved energy helped our ancestors to survive.