Starting Out

I have read, A Brief History of Time. I have more confidence in the story of the Big Bang and the development of stars and planets than I do in the creation myths of any of the religions I am familiar with, but I recognize the uncertainty in the timing. I can't say, down to the year, how old the universe is, or the earth. I can say that the United States declared its independence as a nation in July 1776. There are other beginnings recorded in history, with more or less uncertainty about their timing. And there is debate about when life began, and when life begins for an individual. I have thought about that debate. I do not believe in an immortal soul. I know a lot of people do, and that some have tried to find some measure of the existence of such, without success. I know there are various definitions of immortal parts to humans, souls, spirits, and others. Some acknowledge multiple immortal parts, I have heard, like one for resurrection and another for reincarnation. I see no evidence for any of those in the records of human experience, nor any reason to believe in anything that predates the Big Bang in our observable universe. But I am convinced that things exist now.

Having established that I don't know how or when existence began, I will move on to my personal ignorance about more personal matters. When did my existence begin?

Well, some claim that human life begins with conception. Certainly conception is an important event in creating a human, as we understand the process. On the other hand, the process of conception requires certain things to be in existence beforehand. There have to be sperm, and an egg cell. The sperm could have been around for days, or possibly weeks. Sperm grow from spermatocytes, which grow from spermatogonia. After a spermatogonium divides, one of the daughter cells (Yes, the cells that become sperm are referred to as daughter cells when they form.) becomes a spermatocyte through a differentiation process. From that point, it takes about 74 days for a sperm to mature to the point of being ready for ejaculation. of course, the spermatogonium that made the spermatocyte has been around much longer, possibly going back to the fetal period for the father, but since the only the spermatocyte itself produces the sperm, maybe that should count as the beginning.

But each primary spermatocyte makes four sperm cells, only one of which will fertilize the egg. I can't pinpoint the timing of when the final split between that one sperm and its companion cells occurs, but that is at least a couple of weeks before the sex that causes its ejaculation.

On the female side, the timing is more clear. All the oogonia, which are stem cells that can make more egg cells, are produced in the fetal period of the female, and then, at a certain stage of development, all of them become primary oocytes. That means that the one egg cell that became part of me through conception was produced some time in 1939, though I was born in 1963. That cell had a full complement of chromosomes, but only one quarter stayed with the cell to the end, so it wasn't exactly me. But then, bits of us come and go throughout our lives, so when, exactly, and I me?

The cells that made up the zygote that some claim was the start of me had all formed weeks to years before the acts that got them together began. Did the Continental Congress of 1774 contribute to the formation of the United States? When did this country really begin? History classes start discussion long before the Declaration of Independence, suggesting that, except maybe for the Big Bang, beginnings are not discrete events, but the culmination of processes. Many conceptions are believed to occur without recognized pregnancies. Pregnancy starts with implantation. I think part of the reason for that definition is that the test for pregnancy is detection of the hormone, hCG, which is produced by structures of the conceptus, which don't form for about a week after conception. There is no test for conception, and outside a culture disk, conception cannot be detected. Not even all implantations result in viable pregnancies, so that definition of the beginning of life could be problematic, too.

Once could argue that my life is a form of extension of the lives of both my parents, as cells from each contributed to the cells that developed into me, and that those cells predate me, and go back to the early development of my parents' bodies. The continued existence of the human species if a form of immortality. Or longevity, as the whole species could die out. Even defining the origin of the modern human species is difficult, as different approaches to making an estimate give somewhat different results. Fossils, genetic clocks, archeological sites; which is the best one? And which hominids do we claim as our ancestors?

The book that provoked me into these ramblings suggested the Homo sapiens may be creating its own replacement, Homo deus, a new species that will have different traits and will make ordinary folks like us redundant. I doubt that I, personally, will be around long enough to see if the author was right, but I have contributed to the next generation, as have my offspring, so maybe some small part of me will continue on into the future for a while. And maybe we are still at the beginning.