Everyday Einstein on the possibility of hybrids, chimeras, and even half-human/half-vampire creatures. Read on!
Historically, these classifications were made based on physical characteristics or behaviors. However once scientists gained the ability to sequence genomes of organisms, a whole new method of putting things into groups opened up.
Phylogenetics is a branch of science that uses the genetic sequences of organisms to try and deduce how they are related to one another. For example, by comparing the genetic sequences of different species, scientists have determined that humans have more in common genetically with apes than with slugs (though some humans might be exceptions to that rule).
As with all areas of science, however, there are a couple of points of disagreement about the proper way to handle this classification. One point of contention involves just which parts of an organism’s genetic sequence should be used in these comparisons. Another difficulty is deciding just exactly what is a species. In other words, just how different do two organisms have to be in order to be considered different species? It’s obvious that a wolf and a goldfish are different, but what about two different kinds of mosquitos?
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Before we go any further, we need to understand how reproduction occurs. We’re just going to discuss things at the cellular level, so if you want the higher-level details, ask your parents.
When most multi-cellular organisms reproduce, the reproductive cell (or gamete) of one organism fuses with the reproductive cell of another organism. The cell created by this fusion is called a zygote. The zygote contains a mix of genetic information from each parent. After the zygote is formed, it starts dividing into new cells.
Each of these new cells is genetically identical to the zygote, meaning that every cell of the organism will contain the same mix of genetic information from each parent.