Elephants may have a lower risk of cancer than many smaller animals, an observation that has been … [+]
Here’s some hot news about elephant testicles is something you may have never ever said. But great balls of fire, a new Forum publication in the journal Trends in Ecology & Evolution is on the ball about how elephants may have developed special ways to protect themselves against cancer. This Forum publication, authored by Fritz Vollrath, PhD, a Professor of Biology at the University of Oxford, presented a big argument to look at elephant testicles more closely.
You may not have noticed it, but elephants tend to be very large—large, as in overall body size. At first glance, this “living large” situation could put them at a cancer disadvantage. That’s because every time a cell divides, there’s a risk that it may make a mistake in copying its genetic material and introduce a mutation that ultimately leads to cancer. So, in theory, a large animal like an elephant would have that many more cell divisions occurring and thus have that much greater risk of cancer. But in actuality, the opposite may be the case. Elephants may have a lower risk of cancer than many smaller animals, an observation that has been dubbed Peto’s paradox. This has led some scientists to believe that elephants have some kind of special junk in the trunk or other parts of their body to suppress the development of cancer.
One key may be the TP53 gene complex, which has been dubbed the “Guardian of the Genome.” This gene complex codes for the p53 protein, which initiates a DNA repair cascade or cell trash bin mechanisms to protect dividing cells. Elephants actually have 20 copies of the TP53 gene, which is about 19 copies more than all other animals.
There’s something else up about elephants—namely their testicles. Normally, during fetal development, your testicles—if you have them—started off in your abdomen but then eventually descended like a pair of New Year’s Eve balls to where they rest now: in your scrotal sac. Elephants are different. They aren’t good in the sac so to speak. Their testicles remain undescended deep within their bodies. That’s one of the reasons you don’t see elephants wearing jock straps.
The fact that elephants’ testicles remain deep within their bodies keeps them hot—temperature-wise. The body mass of elephants can serve as giant toaster ovens. Plus, elephants have other reasons to be hot. You don’t tend to see too many elephants at the ski lift in Vail, Colorado. They tend to inhabit warmer climes. In fact, many of their habitats can get quite hot.
That brings up the very cool reason why your testicles ended up descending. When your testicles hang outside, they are less likely to heat up, assuming that you don’t do something unwise with a toaster oven. Although you may think of your testicles as being hot, they really shouldn’t be—at least temperature-wise. Keeping your testicles in a cooler environment reduces the risk of damage to your sperm and all the cells involved in producing your swimmers. And damage to your sperm can result in mutations that can be passed along to your offspring.
And in the Forum publication, Vollrath argued that protecting offspring is a big source of evolutionary pressure. Mutations that allow for healthier and longer-living offspring are more likely to be passed along from parents to children. He wrote that “on chromosomes with damaged DNA, p53 helps stabilise telomeres and thus secures correct crossover, critical for healthy cell divisions.” Vollrath postulated that “elephants initially evolved multiple copies of TP53 not to fight cancer but to protect sperm production in testicles that were increasingly temperature challenged as the animals grew in size during their evolutionary history.” He argued that “Sperm selection is a powerful driver in evolution and a bull’s reproductive success will depend critically on the quality of his spermatozoa.”
Now if you happen to not have very large floppy ears, you may be wondering what all of this has to do with you. After all, you probably don’t have “elephant testicles” as a search term for your news and social media feeds and various Internet sites. And if you do, it may be for a different reason. Keep in mind, though, that humans have a lot to learn from other animals. Humans aren’t necessarily the best at everything. Knowing how elephants can fight cancer can eventually help humans develop new cancer prevention and treatment strategies. And the elephant in the room is that cancer remains a big, big, big threat to human health and lives.