Most of us don't realize how lucky we are to be here, let alone in reasonable health. We mostly know, at least in a historical way, that the first few years of life are tremendously dangerous, and in yesteryear were even more so. The short life spans of times past (and in some places present) were primarily a result of early death rather than those after childhood. Indeed, if you made it through those early years, you had a pretty good chance of living into old age.
What few of us realize is how many fail to even make it to birth. We
have 23 pairs of chromosomes, 46 all told. During the formation of eggs or sperm, we
have to copy each of those 46 chromosomes and divide the resultant 92 chromosomes up
during two cell divisions so that each of the final four cells has 23 different
chromosomes. Tangles and breaks and mistakes abound in the process. At least 20% of
those conceived die from these before birth. Those of us successfully born should
consider ourselves blessed!
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.