Pigs share a number of surprising comparable traits with humans. For instance, we both have hairless skin, a thick layer of subcutaneous fat, light-colored eyes, protruding noses and heavy eyelashes. Pig skin tissues and heart valves can be used in medicine because of their compatibility with the human body. Medical students often practice suturing on pig's feet.
Most of these shared traits are likely due to convergent evolution, happenstance; they aren't the sign of close ancestry. But new genetic analysis suggests that pigs and primates may actually share a hidden evolutionary relationship after all, reports Phys.org.
The new study focused on genetic elements called SINEs (short interspersed elements). SINEs, which make up about 11 percent of human DNA, were once considered "junk DNA," but researchers have now come to believe that analyzing these elements could glean important hints about mammalian evolutionary history.
The most common SINE in humans is called the Alu transposable element. That's important because it is derived from the small cytoplasmic 7SL RNA, and that's important because 7SL RNA is also the source for a common swine SINE, according to the latest research. This would be an unlikely coincidence. Essentially, it lends evidence to the idea that pig and primate evolution have some close parallels that were previously hidden using more conventional genetic analysis.
The upshot of all of this, according to the study's author, is that the suidae family (that is, the swine family) could conceivably be grouped into a family that is otherwise mostly inhabited by primates, at least in terms of 7SL RNA-derived SINEs.
What evolutionary story might this tell about the relationship of pigs and primates? For now, phylogeneticists can only speculate. But it goes to show that our relationships to our animal brethren are often closer than first appearances may suggest. Despite the great diversity of life, there is a string connecting us all together — a string that geneticists are only beginning to learn how to unravel.