Meiosis is the process whereby the sex line cells (which contain 46 chromosomes in humans, just like all the diploid somatic cells) are converted into the haploid gametes (sperms and eggs, which contain only 23 chromosomes). It was first discovered by a student of Haeckel’s, Oscar Wilhelm August Hertwig, in the late 19th century. Essentially, you have 22 (or 23 if you’re female) chromosome pairs which are the same as each other, have a fairly recent common ancestor, and are back-up copies of each other. There are minor differences between the two chromosomes of a pair, which were created either by mutations, or viral additions, or differing epigenetics or past crossovers in meiosis. It would not be too much of an exaggeration to say that what makes an individual unique, and what gives everyone (except identical twins) a unique DNA profile, is a consequence of crossover in meiosis, which was first discovered in 1909 by a Catholic priest who became a Professor of Cytology (the study of cells), Frans Alfons Janssens. It was made famous (amongst biologists) by the American geneticist, Thomas Hunt Morgan. So, what is crossover in meiosis? I now quote from my 1996 book, “The Alternative Life”.
The production of haploid gametes from diploid cells proved to be a very successful trait since it endured and evolved into sex. Sexual reproduction proved very successful as a means of mixing genes. It does so because a randomly-selected chromosome set from one individual becomes mixed with a similar set from another individual to form a new individual. That allowed unique combinations of genes to be created. Another type of mixing can also occur during meiosis. Just before the chromosome pairs in a sex line cell part company to become gametes, they line up alongside each other and hug each other, as if they know that it is the final “Goodbye”. During those final hugs, they often exchange bits of DNA with each other. Breakages and reconnections of DNA chains are quite commonplace during meiosis. The physical intimacy of those exchanges mirrors the physical intimacy of the sexual activities that often make use of those gametes.
Materialist scientists would have us believe that those exchanges of material during ‘Goodbye hugs’, which are not known to occur on any occasions other than during meiosis, happen spontaneously or automatically. I don’t doubt that they happen, nor that they are useful for combining genes on the same chromosome and hence making unique chromosomes, but natural selection alone cannot account for the persistence of this habit under such specialised circumstances. I now quote from Nick Lane’s 2009 book, “Life Ascending”.
The process is known as meiosis, and on the face of it, the division is both elegant and puzzling. Elegant, for the dance of the chromosomes, as they find their partners, clasp them tightly for a time, and then waltz off to opposite poles of the cell, is choreographed with such beauty and precision that the pioneers of microscopy were scarcely able to avert their gaze, concocting dye after dye that captured the chromosomes in the act, like grainy old photographs of an acrobatic dance troupe in their heyday. Puzzling because the steps of the dance are far more elaborate than anyone would have expected from that most utilitarian of choreographers, Mother Nature.
A choreography, and especially an elegant one, requires constant practice and repetition, under the guidance of a choreographer. The idea that the same choreography happens spontaneously in gazillions of cells across the entire planet, unless there is some sort of mysterious communication of habit involved, is frankly preposterous. As I say in my unpublished book, “Lamarck’s Due Darwin’s Luck”, in a more generalised context: “Life’s organising ability, in the form of the orchestration of molecules complete with choruses of gene expression, remains unfathomable.”