Biomedical Engineering Reference
In-Depth Information
to classify gorillas within the hierarchy of organisms (Animalia: Chordata:
Mammalia: Primates: Hominidae: Homininae: Gorillini: Gorilla). Specifically,
you can identify an animal as a gorilla without knowing that a gorilla is a type
of mammal. You can classify a gorilla as a member of Class Gorillini without
knowing that a gorilla happens to be large. One of the most common mistakes
in biology is to confuse an identification system with a classification system.
The former provides a handy way to associate an object with a name; the latter
is a system of relationships among organisms.
Still, it is impossible to forget that every species is populated by members
that are similar to one another. When you see two squirrels playing in a tree,
you cannot help but notice that the two squirrels are virtually identical. You
can see their similarities, even if you cannot recite the biological features
that define the squirrel species. You recognize them as squirrels because
of their similarities to each other. You correctly infer that the two squirrels
are characterized by a shared collection of “squirrel” genes. Likewise, the
species of tiger is characterized by a set of genes that produce tigers. Every
species on earth can be characterized by their genes. You go one step further,
and you infer that if we had all the genes sequenced for every organism on
the planet, we could create a complete and accurate classification for all the
terrestrial life forms. Is this last inference correct? We will be discussing this
topic in Chapter 3, The Tree of Life.
