Wednesday, June 7, 2017

How are humans made?

I'm not sure if this question is asking about how the first humans were made/appeared on Earth, or how a new human is produced.  I'll answer the second option because the science is more concrete.  
Males and females each produce sex cells known as gametes.  Males produce sperm, and females produce eggs.  Each gamete carries exactly half of the genetic code.  This is called a haploid cell.  In humans, that means each sperm and egg carries 23 chromosomes.  
The female menstrual cycle will release an egg into the fallopian tube about once every 28 days.  Sperm will swim to meet the egg.  When the sperm and egg join, this is called fertilization.  The two haploid cells are now joined, and a new diploid cell has been created that has its own unique genetic profile.  The fertilized egg is now known as a zygote.  It will eventually make its way to the uterus where it will implant itself and begin going through mitotic divisions for another 9 months.  Labor will begin, and a new human baby will be born.  
I would like to bring up a debate of sorts regarding when that new life is considered a human.  Some people believe that the child is a full human only after it is born.  Other people believe that the new human life is created the moment fertilization occurs because that is when the signature 46 chromosomes are present.  Still others believe that the new life is human at some point between those two times.  
https://www.princeton.edu/~prolife/articles/wdhbb.html

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