The ability of both animals and people producing numerous healthy offsprings is called fertility. This term was first applied only to the female; however, with better understanding of the reproductive mechanisms, the importance of the male's fertility too is gaining importance. A person or animal that cannot produce offsprings is considered to be infertile.
With humans, fertility in a person depends on various issues like sexual behavior, nutrition, culture, endocrinology and instinct. Along with this timing, emotions, economics and the way of life all play an important part in the fertility of a person. Animal fertility also follows such factors and displays great mechanisms. Vegetables in farmlands and plants too experience fertility, which is the capacity of producing large yields of fruits, seeds or vegetables.
The term fertility rate is the measure of number of children per woman. This was first considered a good indicator of population growth. However, it is not so much so in Asia now. This is due to selective abortion and various other factors that the number of women here is reducing drastically. With this, the fertility rate is no longer considered to be an authoritative in measuring population growth in the Asian countries of China, Myanmar and India.
The hormonal cycles in both men and women help to tell when the woman can conceive, and when the man is very fertile. Though the hormonal cycle of the female is constant, about twenty eight days long, the male cycle is variable. The fourteenth day of the female cycle is the most fertile period for females. This is because they ovulate at this time. There is no such period for men to ejaculate and produce sperms; it is produced any time of the month. However, it is their libido that may dip and this is what scientists infer to be their hormonal cycle.
It is during the fourteenth week of fetal growth that a woman's eggs forms in the ovaries. They remain there till puberty where the eggs mature one by one. On ovulation, the egg bursts from the ovary. This may sometimes because a small and sharp pain called mittelschmerz. The egg breaks down within twenty fours into its protein components if the egg is not fertilized by a male's sperm. These components are then reabsorbed by the body. As the quality of men's sperms deteriorates after 35, it is recommended by fertility clinics that they freeze their sperms before this if they plan to have kids later. However, there are men who produce healthy sperms long after 40!
Women are most fertile in their twenties, and starts diminishing after 30. It is better to get pregnant at a young age as the possibility of miscarriages increases with age. Even the possibility of birth defects in the baby increases with the age of the mother. So by multiplying the possibility rate of a conception with the miscarriage rate and the birth defect rates give the best possibility of a healthy birth. This figure; when multiplied by it gives the rough possibility of additional children.
Through the last decades science has struggled to estimate the age of the human race. Obviously, evolution would insist this occurred a long time ago, as it would take an incredible span of time for the first human-like creature (the cave man or monkey man) to develop into the sophisticated humans of today.
First, it must be observed that current estimates for the age of mankind are still all over the board. The lack of reliable dating methods for organic material is a serious challenge for all paleo-anthropologists. This might surprise you, but the only reliable dating method for organic material is Carbon-14 dating. This procedure can date organic material such as bones and teeth accurately but only to a maximum of 25,000-30,000 years. Dating older organic material is nothing more than guesswork. In many cases these guesses rely on ?leap of faith? assumptions by dating the rocks found near the organic material in question, wildly asserting these rocks were formed at the same time as the bones/skull/teeth were deposited. Obviously that is not science, but only wishful thinking.
Recently the advance of genetics has opened a new pathway to estimate the age of mankind through the analysis of human organic material. By comparing samples of currently living humans with well dated DNA samples from the past, an estimate can be made for the rate the human DNA record changes. Applying this estimated natural mutation rate to a representative sampling of the DNA of today's world population, allows to estimate how much time would be required for today's human DNA to mutate (?deteriorate?) from a common ancestor. As every cell in the human body contains the combined DNA from both the father and the mother, analyzing this DNA would not allow to trace the separate ancestry of the male or female. However, two portions of human genetic material do not recombine in reproduction, namely:
1) Mitochondrial DNA (mtDNA) This DNA resides in the so called mitochondria structures, outside the cell's nucleus. Mitochondria are the ?cellular power plants.? They convert food molecules into energy. Mitochondria contain DNA that is independent of the DNA in the chromosomes that is stored in the cell nucleus. Both men and women get nearly all of their mtDNA only from their mother. In the late 1980s and early 1990s a number of studies examined the mtDNA of women all over the world. These concluded that all women descended from one ?Eve? who lived within the last 200,000 years. Refinements in measurements lowered these original estimates to 135,000 years and finally to less than 100,000 years. These studies not only suggest a much younger age for humanity than previously assumed, but also indicate that all humans descend from ONE woman, ruling out that humans would have simultaneously evolved in multiple locations/regions.
2) A large segment of the Y-chromosome. Only men have a Y-chromosome, most of which they receive only from their father. Since 1995 studies have been conducted to trace genes on this Y-chromosome to determine the age and descent of males. Various studies all indicate younger ages for mankind. What may well be the most reliable study published so far, calculates a common ancestor to modern man at between 37,000 and 49,000 years ago.
These studies also indicate that genetically all humans are much more alike than one would predict from Darwinian theory. Examinations of the genetic sequences of diverse modern human populations reveal minor differences, if any at all. One scientist noted: ?It's a mystery none of us can explain.? All this evidence suggests a recent origin for modern humans, far more recent than evolutionary theory would allow.
Evidence from archaeology and anthropology is consistent with such estimates for the age of humanity. Sophisticated works of art first appear about 40,000-50,000 years ago, and evidence of religious relics and altars date back no earlier than 25,000 years.
Archaeological finds of leftovers of human habitation date back only 15,000 years ago. Claims for older finds are rarely presented.
Accounts in the Biblical book of Genesis mention the descendents from the first man, Adam, through Noah, Abraham and Moses. Based on the literal reading of this data, it can be calculated that Adam was created by God a little over 6,000 years ago. This is also the date claimed by Six Day Creationists for the actual creation of the world. Other scholars point out the common practice of ancient Hebrew culture to skip generations in the genealogical records. Thus it is conceivable there were substantially more generations between Adam and Abraham than recorded in Genesis. These scholars generally theorize that, based on these records, Adam and Eve could have lived 8,000 to even 25,000 years ago. These views are the basis of the suggested range of 6,000 to 25,000 years old for the age of mankind. These Biblical estimates are surprisingly consistent with those supported by archaeology.
Whichever way one looks at the data, one conclusion is inescapable: as time progresses, estimates from science come ever closer to the age inferred by the Biblical accounts
Both Melvin Ng & Rob Vandeweghe are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.
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Rob Vandeweghe has sinced written about articles on various topics from Religion, Environment and Religion. Rob VandeWeghe is a sceptic turned Christian. More evidences for Christianity are available at