Differences & similarities: Human & Animal Anatomy

There are an enormous amount of traits that humans and animals share; this is because of the evolutionary process of inheriting characteristics and traits from successive generations that all lead back to a common ancestor.

Humans and animals share the same basic muscles and bones, but they appear at different sizes, proportion and ratios based on the animal. Bipeds are animals that traverse their environment on two legs, like us humans. Quadrupeds are animals that use four limbs to travel around like dogs, horses, cows, cats, and many other four limbed mammals.

In terms of locomotion, evolution has developed two very common forms of movement using the same muscles and bones. As shown below, humans and dogs share the same groups of bones and muscles even though they have completely different forms of locomotion. 

In diagram A, a human man is shown next to a dog, the bones are highlighted on each animal and they are shown to be the same bone but in different proportions and ratios. What many people would think to be a dog’s upper leg is actually its lower leg, and what many people think is it slower leg is actually the equivalent of a human palm.  

Using the same two animals as a comparison, human hands and dog paws when seen side by side share the exact same bones in different places. As seen in diagram B the thumb of the human is a vestigial part of the dog’s foot, meaning a mutation from a previous ancestor that still appears in subsequent generations but is no longer used for the same purpose. 

In the comparison shown below in diagram C, the same bones shared between humans, large cats, and horses are pointed out, it is clear that many mammals have very similar skeletal structures regardless of their form of locomotion.  Like the common misconception about dogs, the upper leg of most quadrupeds is hidden behind layers of muscle and fat, this is why colour coded Skelton diagrams are the most digestible forms of delivering information about the similarities and differences between human and animal anatomy. 

Another very interesting area of anatomy that shares similarities and differences across multiple different species types is the bones of the hand. The human hand can be seen in many other animals such as bats, birds whales, horses, cats and other mammals. The diagram below shows how the same bones are reconfigured in other species to suit different purpose, including completely different types of locomotion including deep sea diving and swimming and even flight. It is interesting to see how the bones that we would see as the fingers can be fused together to create bird wings, or they can splay out to create bat wings. In the example of the horse, the ‘foot’ of the horse that the hoof appears on is actually just one ‘finger’ bone. 

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Bibliography 

Anon., n.d. Animal Antomy. [Online]
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Brain, M., 2014. How Evolution Works. [Online]
Available at: http://science.howstuffworks.com/life/evolution/evolution.htm
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Introduction to Animal Anatomy. n.d. [Film] Directed by Marshall Vandruff. s.l.: Gnomon Workshop.

National Libary of medicine , 2014. National Libary of medicine. [Online]
Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899734/
[Accessed May 2014].