After
your Thanksgiving feast, did you crash? Many people do, and it has been blamed
on tryptophan, an amino acid in turkey. It’s possible you have the cosmos to
blame for that.
According
to an internet search, “Tryptophan is an essential amino acid the body uses to
make proteins, the neurotransmitter serotonin, and the sleep-related hormone
melatonin. It is not produced by the body, so it must be obtained through diet
from foods like turkey, chicken, nuts, and soy.” This, some people claim, is
why you feel sleepy after a Thanksgiving meal that includes turkey.
Astrobiologists,
specialists who seek evidence of life elsewhere, and biologists who study the
origins of life on Earth suggest several ways life might have started here. One
idea is known as panspermia. Panspermia says that life on Earth was seeded from
space, most likely by organic molecules delivered to Earth via asteroids, comets,
or meteorites, which carried these molecules.
Earth
spacecraft have returned samples from two asteroids, Ryugu and Bennu. They have
found 90 amino acids, including 14 of the 20 used by life on Earth. In
addition, they have found all five of the bases, adenine, guanine, cytosine,
thymine, and uracil, which make up our DNA.
One
of the amino acids on asteroid Bennu was tryptophan. José Aponte is an
astrochemist at NASA's Goddard Space Flight Center who coauthored a study on
the sample returned from Bennu. On finding that sleep-inducing molecule on
Bennu, he said, "Finding tryptophan in the Bennu asteroid is a big deal,
because tryptophan is one of the more complex amino acids, and until now it had
never been seen in any meteorite or space sample."
Many
biologists and other scientists who study the formation of life on Earth
believe that it rose independently here. But the delivery of important organic
and other biologically important molecules to our planet from space must surely
have played a role. Before you say life here didn’t come from the stars,
remember that most of the molecules in our bodies were formed in stars, so we
are literally star dust.
Each month, I write an astronomy-related column piece
for the Oklahoman newspaper. After
it is published there, I post that same column to my blog page.
This is reprinted with
permission from the Oklahoman and www.Oklahoman.com.
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