Fish Are Friends, Not Food

I recently came across a strange species of fish called the pacu, a relative of the piranha known for its mythical taste for human flesh. The pacu is native to South American freshwater and is well known for its teeth, which are scarily similar to human teeth. Pacu can reach up to 3 feet long and weigh up to 55 pounds in the wild. Pictured below is a massive Black Pacu (Colossoma macropomum). 

The pacu has been blamed for the castration of several fishermen wading in the water trying to get a bite. Ironically, the only bite they got was one on the testicles. We now know it is not the pacu who is responsible; however, the most interesting thing about this fish is not the mythical taste for human testicles, but its uncanny similarity to humans. Unlike its relative, the piranha, the pacu does not have sharp pointed teeth. Instead, it possesses a set of square, straight teeth very similar to human teeth as seen below. Pacu feed on seeds and nuts. The outer shells of its diet require teeth stable and blocky enough to bite through the hard shell, hence why pacu do not have razor sharp teeth like the piranha.

I am not one who believes in coincidence very often. I strongly believe in everything has a purpose to it. So because of the way I think, I automatically said to myself, we must be related to these fish in some way or form. 10th grade biology taught me that everything on Earth evolved from a common ancestor, so I know somewhere along the line we are related to the pacu. But the issue in question is not are we related, it is how closely related we are.

One way to answer this is to look at the anatomy of fish and humans and compare the similarities. In an article written by Joe Palca of NPR, Neil Shubin claims that every component of our being is a variation seen in fish. He suggests this after spending years in the Canadian Arctic searching for a very important part of the story of sea-dwelling animals making the transition to land. He discovered Tiktaalik (seen below) in 2004. Dubbed a “fishapod”, Tiktaalik (who lived 375 million years ago) may have been the missing link to finding out how we got to where we are now as humans.

From the two pictures above, there are clear similarities in the bone structures of Tiktaalik and modern humans. Both have a rib cage, joints, shoulders, a neck, and a skull to encase the brain (the human brain is much more complex, but Tiktaalik shows evidence of the beginnings of a much more complex brain than earlier animals). The most interesting bones found in Tiktaalik are not the ones listed above, but the fins as seen below. As you can see, Tiktaalik has a very primitive human hand with a humerus, radius, ulna, and what looks like to be the beginnings of a set of fingers. Tiktaalik’s fin bones show the beginning of the long evolutionary process from fish transitioning into many of the amphibians, reptiles, birds, and mammals we see today. Furthermore, in a series run by PBS called Your Inner Fish, Neil Shubin is featured as he explains our evolutionary process from sea-dwelling creatures. This short clip from one of the three episodes explains the finding of Tiktaalik.

So after seeing the evidence that Tiktaalik may be our earliest fish ancestor, I was still left wondering how possible it is that humans and pacu are related in some way. I would argue that it is quite possible. In order to explain that argument, I must first explain the evolutionary process. I remember from my 11th grade anthropology class that one theory of evolution argues that many variations of a species inhabit our planet at once, but natural selection causes the weaker, less well-adapted species to go extinct. Tiktaalik’s successors likely would have broken into several variations, some big, some small, some fast, some slow, some herbivores, some carnivores. How possible is it that somewhere along the line, humans and pacu shared a later common ancestor than Tiktaalik? Such an animal would have to have use for a set of teeth to break hard objects and it would have to be amphibious in order to eventually break into land-dwelling species and sea-dwelling species.

As of now, the only way to truly know how closely related we are to pacu and other fish would be to conduct a gene test between the species. A gene test would allow us to look at the genetic sequential similarities and be able to put a percentage on how similar they are. For example, chimpanzees and humans are about 96% similar in their DNA. Clearly pacu and humans would be far less than that, but I believe the percentage has the potential to be much higher than most would assume. Shubin and his team continue to learn about Tiktaalik and its importance to human evolution and the evolution of land creatures as a whole. I believe a genetic comparison between humans and pacu would not only surprise a lot of people, but would also reveal a lot about our origins as humans and our path to where we are today. Additionally, it may also put into perspective just how intertwined we are with the rest of our world.

Images:

http://www.gillhamsfishingresorts.com/wp-content/uploads/2013/05/Black_Pacu_0059_Rob_Eustace_pacu11.jpg

https://evolvingcomplexityii.files.wordpress.com/2009/06/vampirefish_03_hookediv2.jpg

http://lh5.ggpht.com/-1_eM4uU0m0w/UvxRCKY4oVI/AAAAAAAAv7E/0gbipS-Q2T8/pacu-fish-6%25255B6%25255D.jpg?imgmax=800

https://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Tiktaalik_roseae_life_restor.jpg/1280px-Tiktaalik_roseae_life_restor.jpg

http://www.earthhistory.org.uk/wp-content/Tiktaalik.jpg

https://lh6.ggpht.com/FApEfeB2L5MIenXGStctz6D4qktObyU8g9TKL6v3QIOldtniFY6NsR6ccq7eToGbhw=h900

https://janetkraydotcom.files.wordpress.com/2014/04/tiktaalik2-e1397347863621.jpg

 

3 thoughts on “Fish Are Friends, Not Food

  1. Brian Dougherty Post author

    I would disagree with the notion that finding new evolutionary links to other animals would not lead us closer to finding out how we got to where are today as humans. I think it would be extremely important to find those links because, while we have a fairly good idea of how we got here, we do not know the whole story. Yes, we evolved from primates, but take it further than that. What did primates evolve from? What did the predecessor of primates evolve from? So on, and so forth. Better understanding our journey would not only teach us more about ourselves and our own history, but also the history of the world and our place within such a big world, much of which is still unknown to us.

  2. Morgan Alexandria Parker

    This blog was very interesting. I never even thought about or noticed the similarity between fish and humans. I do believe everything comes from similar genetics and I liked how you tied that into your post, but I am not sure I believe the similarities between fish and people could lead us to find how we came this far. Definitely something I would like to look into further though! Thanks for the post, very cool.

    http://www.debate.org/opinions/were-humans-once-fish
    Here’s a link to a debate whether or not humans were once fish!

  3. Julian Eisenberg

    Humans like all other animals have evolved one way or another from an earlier version of ourselves. Whether its the Paco or the chimpanzee, I know that our genetics, with out a doubt, intertwine with other species. Although, I find it very interesting to even consider a sea creature like the Paco to evidently be so closely related to us. I would have to agree that fish are friends not food (although sushi is a great food alternative).

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