Aseel’s Reviews > Your Inner Fish: a Journey into the 3.5-Billion-Year History of the Human Body > Status Update

But there is a big limitation to working with
fossils. We cannot do experiments on long-dead animals.
Experiments are great because we can actually manipulate
something to see the results. For this reason, my laboratory
is split directly in two: half is devoted to fossils, the other
half to embryos and DNA. Life in my lab can be
schizophrenic.

From common parts came a very unique
construction. We are not separate from the rest of the living
world; we are part of it down to our bones and, as we will
see shortly, even our genes.

Do the facts of our ancient history mean that humans are
not special or unique among living creatures? Of course not.
In fact, knowing something about the deep origins of
humanity only adds to the remarkable fact of our existence:
all of our extraordinary capabilities arose from basic
components that evolved in ancient fish and other
creatures.

Finally, the full complement
of wrist and ankle bones found in a human hand or foot is
seen in reptiles more than 250 million years old. The basic
skeleton of our hands and feet emerged over hundreds of
millions of years, first in fish and later in amphibians and
reptiles.

The important, and
often surprising, fact is that most of the major bones
humans use to walk, throw, or grasp first appear in animals
tens to hundreds of millions of years before.

the
earliest creature to have the bones of our upper arm, our
forearm, even our wrist and palm, also had scales and fin
webbing. That creature was a fish.

The bones of the front fin of Tiktaalik— a fish with a
wrist.

All creatures with limbs, whether those
limbs are wings, flippers, or hands, have a common design.
One bone, the humerus in the arm or the femur in the leg,
articulates with two bones, which attach to a series of small
blobs, which connect with the fingers or toes. This pattern
underlies the architecture of all limbs.

The simplest way to teach students the nerves in the
human head is to show them the state of affairs in sharks.
The easiest road map to their limbs lies in fish. Reptiles are
a real help with the structure of the brain.

It turns out that being a paleontologist is a huge
advantage in teaching human anatomy. Why? The best road
maps to human bodies lie in the bodies of other animals.
The simplest way to teach students the nerves in the
human head is to show them the state of affairs in sharks.
The easiest road map to their limbs lies in fish. Reptiles are
a real help with th