Jazmean Williams
AP Biology
Phylogenetic Analysis
How Closely Related are
Dogs to Humans?
The basis of this
Phylogenetic Analysis revolves around the domestication of dogs
(Canis lupus familiaris) by humans (Homo sapiens). While there is no
clear date as to when dogs were domesticated by humans, scientists
know that dogs have been domesticated for a long time. Scientists
also know that early human hunter-gatherers used dogs to perform many
roles such as hunting, herding, and providing protection. This leads
to the conclusion that humans domesticated dogs in order to improve
their style of living. But why dogs? Why not choose another animal to
domesticate? The answer lies within the idea of companionship. Dogs
are known today as being man's best friend, however, becoming
someone's best friend takes time and an immense amount of effort.
Could it be that early humans were willing to put forth the effort in
order to find another species they could relate to besides their own?
Could the domestication of dogs begun with the intention of
companionship instead of the completion of menial labor and
protection?
To figure this out, three
genes that exist in both dogs and humans will be analyzed and
compared on a Phylogenetic Tree to see how closely related dogs and
humans are. The closer in relation the dog and human are in the tree,
the more alike they are, and the more likely they are to develop a
bond with each other. The three genes that will analyzed are the
PHOX2A gene, the TGIF1 gene, and the PROP1 gene. The PHOX2A gene
deals with the development of the nervous system which affect bodily
functions such as heart rate and breathing. The TGIF1 gene provides
instructions to develop the front part of the brain. The PROP1 gene
helps the pituitary gland release hormones that aid in growth and
reproduction (along with other bodily functions). If the nervous
system and front part of the brain develop in a similar fashion ,
then one an infer that there will be similar bodily and brain
functions between the human and the dog. This applies too if the
human and the dog grow and reproduce in a similar fashion. Also, in
the tree, an outlying animal (the Zebrafish) will also be used to
further help compare the dog with the human on the tree.
After doing the
Phylogenetic Tree for each gene, it shows that the dog and the human
share a recent common ancestor. Because both the dog and human share
a more recent common ancestor, they share common structures and even
patterns of behavior. All three animals share a common ancestor, but
it is the dog and human that is most closely related due to both
species having a more recent common ancestor with each other.
The results and inferences
of this Phylogenetic Tree Analysis is similar to the information
presented in scholarly articles. In the National Geographic, Jane J.
Lee wrote an article about how the dog and human genomes evolved
together in parallel evolution. Weiwei Zhai, a genetics researcher
Lee references in their article, used genes that helped in the
transport of neurotransmitters and cholesterol processing to compare
the two species. He found that those genes were selected for in both
humans and dogs. Zhai also found that there are cancer-related genes
that are evolving together in humans and dogs. Weiwei Zhai believes
this parallel evolution occurred due to the fact that dogs and humans
lived closely together in the same environment. There is still debate
however on whether the parallel evolution between humans and dogs are
unique or if they exist in other domesticated animals as well.
The Huffington Post also
reported an article about how dog brains process voices and emotions
like humans which further supports the idea of humans and dogs being
alike. Attila Andics, the researcher cited in this article, proposes
that voice recognition between humans and dogs can explain why
communication between the two species is so successful. He also
proposes that this discovery can lead to an explanation of the
“unique bond” humans and dogs have together.
The evidence provided from
the Phylogenetic Tree and from the researchers aforementioned can
solidify the possibility that dogs were domesticated with the
intention of companionship and not labor. The companionship between
the dog and the human could then lead off to a symbiotic relationship
between the two species which is shown to have happened due to
present day conditions. This way of thinking supports the idea that
two species that live in the same environment will not always result
to competition, but can work together to form a relationship that
benefits the both of them.
Primary Sources for Discussion
Gene Sequences Used
Software Used
Your comparison of humans to dogs I found very interesting especially after reading about how humans and dogs come from a common species. Do you happen to know what the common species is? Also, the fact that humans and dogs evolved together in a parallel evolution is very interesting. Have you found research on other genes, besides the cancer related gene, that evolved with humans and dogs relatively at the same time?
ReplyDeleteThe common species for dogs and humans is not known because the mammalian lineage is still being worked out. But scientists predict that the common ancestor for dogs and humans had a brain the size of an egg.
DeleteI would have to find more information if there are more genes that evolved relatively the same time but I would infer that there would be more due to the fact that dogs and humans lived in close environments for a long period of time.
Overall, this article is very interesting and well-worded. When you were preparing a question for this article, did you think of using any other domesticated animals for the comparison? For example, a cat could also be an interesting animal to research about in comparison to a human.
ReplyDeleteThank you! And to be honest, I didn't think of any other animal to try. Dogs were the animals I chose because of the long history they had with humans. But cats would be great species to try to see if there's a pattern.
DeleteOverall I found your article to be extremely interesting. I loved how you discussed and compared the original purpose for domesticating dogs to whether it was for companionship or labor. In order to solidify your results, choosing three genes to compare was extremely beneficial for your article. One question I would have is, are there any other animal species that has a companionship with humans that would not be so similar to humans at first glance but genetically they are? Maybe this could be used as a basis for further research.
ReplyDelete