Humanity. Homo sapiens. Mortals. More than 150 years after Darwin published On the Origin of Species , society continues to turn to biology to separate man from beast because humans like to believe they are special. But just how special are we really? When scientists first began to examine human DNA in fine detail, many thought it would finally close the question of what makes us human: our uniqueness would be written in the four-letter code that constitutes our DNA. At the time, no one knew how many genes humans had, with some scientists estimating the number to be upward of 150,000 genes, reasoning that such a complex species would need more genes than simpler organisms. As the data was published, it quickly became clear that ( A ) truth. Humans have only around 20,000 genes that code for proteins; one tiny species of roundworm, C. elegans , has 18,500. Furthermore, our genes aren't significantly different from those of our closest animal relatives. Today, it is a pop-s...
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