1. How we became endurance runners

2.  The first people on earth climbed in trees, walked on 4 legs, and were covered in hair.

3.  The food that people ate was in the trees. It was easier for humans to climb in the trees with four legs, like a monkey, than to walk on twotrees

5.  The forests turned into hot, dry plains.plains.

7.  They didn’t have a lot of weapons.

9.  People could run farther with two legs instead of four.

10.  Humans also had to outrun predators because they couldn’t hide in the trees anymore.

11.  Each one of these could be a different slide or if it would be easier you can put more than one together on a slide.

12.  As Team One’s article mentioned, there were many potential reasons why our earliest ancestors left the trees and became bipedal.article

13.  A few such theories state that we may have sought to reach higher elevations in foraging, see farther over tall grasses, reduce the exposure of solar radiation, or extend our foraging areas beyond the forests and into the grassy savannahs.

14.  Some scientists think that our earliest chimpanzee ancestors used to free their hands for carrying food or infants over long distances.

15.  By studying species’ evolutions in skeletal figure over time, we can see how humans have adapted to become dominant endurance runners

16.  Daniel Lieberman likes to classify a few different stages throughout time to illustrate this point. He argues that Stage 1, the earliest hominins (closely related to chimpanzees), were occasional bipeds— only walking on two feet for some physical benefits related to everyday lifestyles.stages

17.  The real changes in skeletal figure were seen in Stage 2, or in the Australopiths, about 4 million years ago. Much of the changes in this period were related to the cranium due to changes in diet (more protein).

18.  Feet started to show longitudinal arches and a wide pelvis with efficient hip abductors. Medially positioned knees and enlarged lower extremity joints counteracted higher stresses caused by bipedalism.

19.  The general picture of the Australopiths is that they were habitual and effective walkers and climbers.

20.  Stage 3 describes Homo, and the final evolution of the skeletal figure. One theory of how we became endurance runners is that Homo was selected to become runners and not walkers through physical evolutions.

21.  The mechanics behind running differ greatly from walking; Homo saw a large proportion of these features include potential adaptations for storing and releasing elastic energy such as a long Achilles, and evidence for a close- packed calcaneo-cuboid joint, which helps the longitudinal arch function as a spring.

22.  These evolutions affect the foots strike impact and ability to generate more force pushing off of the ground when running.

23.  Animals have hair all over their body and humans do not. Having no hair helps us to run longer for many reasons.

24.  Humans can lose heat faster when they run since the don’t have all of the hair trapping it in. When you are able to lose the heat faster you can run for longer since your body is not overheating.

25. Humans also sweat instead of pant. Sweating is separate from the respiratory system so while we are breathing we are also perspiring giving an extra edge over animals who can only pant.

26.  Due to the loss of hair on major exposed regions of humans’ bodies in early stages of our development: not maintained, a human could overheat and not be able to endure long distances of running.running.

27.  An important feature to realize is that the skin is the major organ that controls heat and moisture to and from the surrounding environment: providing the first barrier between the organism and the outside world. world

28.  Some studies have shown that those of darker skin descent, such as Africans, came from ancestors who experienced shortages of high-caloric food that is important in maintaining relatively constant core temperature.

29.  Darker skin color, which absorbs better visible part of solar radiation so that organisms of primitive humans get additional energy in the form of heat, helps maintain extremely high levels of metabolism that humans must preserve.preserve

30.  Therefore humans that did not have easy or immediate access to supplementary food supplies have shown darker skin color that could provide them more energy through the use of solar radiation, which would allow them to have a better maintenance of their body temperature: whereas most Europeans for example, aren’t as dark as Africans because they obtained food from other means, with no need for long distance running.

31.  And that is how we became endurance runners.