Welcome to the Biology Tips Daily - another tip and another day.
You know that past history contributes to the current state of affairs. You probably learned that in, well...history class! Life also has a history and that history profoundly influences all the biology we observe today.
The evidence is indisputable that eukaryotic cells, the ones that compose your body, were not the first kind of cells to exist. That honor goes the prokaryotic cell, which arose about 3.5 billion years ago and, despite its relative simplicity, continues to dominate the planet. One of the most intriguing problems in biology is the origin of the more complex eukaryotic cell about 1.5 billion years ago. To solve this mystery you must understand that everything studied in biology has a history. Not much biological arises spontaneously, full blown and functional.
Scientists generally accept that eukaryotes arose from prokaryotes that ingested other prokaryotes but did not digest them. This is the endosymbiont theory of the origin of eukaryotes. Some of the parts of modern eukaryotes were independent prokaryotic cells that combined with other cells and evolved over long periods of geological time to become "eukaryotic".
In fact, it was recently reported that the endosymbiosis process is occurring among some microscopic organisms found on an Australian beach, giving scientists an opportunity to observe biological history in the making!
History can also help explain why some features of organisms seem poorly designed. If you were an engineer, it is unlikely that you would design the human birth canal as it is. Though the birth canal is quite "stretchy", babies have ridiculously large heads compared to the width of the birth canal, even when it is maximally stretched. While being born may be a momentous event in your life, it also causes great pain and sometimes even mortality to mother and child.
If an engineer had designed a "baby delivery system", a zipper across the mother's abdomen would have been the way to go. At delivery time, simply unzip the mother's abdomen, reach in, pull out the baby, and re-zip the zipper to close the abdomen. Whopping big baby heads are no longer a problem and the process is swift, painless, and safe for all.
So why the suboptimal solution in reality? In a word - history! The offspring of our primate ancestors had a relatively small head compared to their mother's birth canals so zippers or other contrivances to the same end were unnecessary to insure the safety of all parties. Just as we inherited our forward facing eyes, our manipulative hands, and our inquisitiveness about the environment and each other from our primate ancestors, we also inherited that darn birth canal.
Despite the problem it posed for us, a species with ridiculously large brains as newborns (and as adults for that matter), we were biologically limited to modifying our primate ancestor's anatomy, not totally reinventing a solution as an engineer would do.
Who would have guessed? Biology is an historical science. Keep that in mind as you develop your biological sense.
Until then, stay tuned for more biology tips.
Seize the Day!
Dr. Wayne Huang
"The Rapid Learning Coach"
BioTips@RapidLearningCener.com
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