I’ve been looking into the science of Human Embryology to see exactly what is known at this point, at least at the level of university courses on the subject.[1] Especially interesting, of course, is the time from the sperm finding the egg to the time the fertilized egg heads off down the fallopian tube.
Of particular interest are the metabolic functioning and the conversion from mitosis to meiosis in the egg.
The metabolic function exists in both the living sperm and egg. Both sperm and egg are dependent upon their internal source of energy to keep their metabolism going. If the sperm or egg does not reach fertilization, the metabolic system ultimately exhausts the internal source of energy, and the sperm or egg dies.
If, however, the fertilization process occurs, the egg’s metabolic process continues longer, and continues as the fertilized egg goes through the fallopian tube. In the fallopian tube the egg is metabolically assisted by external metabolites acquired from the fluid which fills the tubes. It is thought that this fluid is necessary but insufficient to fully sustain the fertilized egg, and the egg must seek to attach to the uterus wall in order to continue its metabolism and life.
The egg itself has to perform mitosis twice before accepting a sperm. Mitosis splits the egg’s DNA, making a single strand available for the combination process. When the sperm is accepted, the egg and sperm engage in a combination and meiosis, after the sperm sheds its tail.
What has happened is this: the sperm and egg are both alive, with very short life expectancies. Until, that is, they combine. At that point they have an extra life span due to a prolonged metabolic function. That prolonged metabolic function supports not just the life of egg/sperm combination, but also the changeover to meiosis in order to combine the two DNA types, and divide the cells using the combined DNA. The DNA now is the DNA of a new, unique individual, metabolically alive and functioning normally at the first stage of its life.
The dividing cells have the full capacity to become all the many structures and functions of the independent human. But for the duration of the pregnancy, of course, the new human is dependent upon the mother for nutrition for its metabolism (and probably other things).
Inherent in this process is a class of signaling and timed signals. Signaling is apparent in the sperm’s entry, from the contact with the egg’s exterior and being allowed to pass through, to the activation of the egg’s defense system which prevents entry by any other sperm. The sperm is signaled after entry into the egg, that it is time to lose its tail. The egg is signaled to stop mitosis and after combination with the DNA from the sperm, to proceed to meiosis. (The three unused products of the egg’s initial mitosis become inert spots in the egg, called “polar bodies”). The egg is removed from its perch as a follicle by the wiping action of the fronds on the end of the fallopian tube which surround (but don’t attach) to the ovary. When the egg is removed, it is taken down the fallopian tube to the uterus.
Comments:
The details of what happens at each stage seem well documented and go well beyond the summary given here; but the reasons (causal forces) are entirely missing from the text books.
Because this does not happen in dead eggs or with dead sperm, then the abstraction called “life” is necessary. Life is passed down through the fertilization process. Much, if not all, of the action is controlled not by the four forces of physics or entropy, but by directed forces which have specific functions, respond to specific signals at specific times, signals which exist in multitudes and which are interdependent and have the apparent quality of obeying a master controller. And the new cells have the capacity to become innumerable cell types and organs, from blood, bone and heart/lung/liver systems, to neural signaling complexes and thinking brains.
Notes:
1. Information contained above is compiled from the following sources:
Schoenwolf, et al; “Larsen’s Human Embyology”, Fifth edition; Elsevier; 2015.
Dudek; “Embryology”, Sixth Edition, Board review series; Wolters Kluwer; 2014.
Mitchell, Sharma; “Embryology”, Second Edition; Churchill Livingstone; 2009.
Langman; “Medical Embryology”; Fourth Edition; Williams and Wilkins; 1981.
Granville Sewell; “Entropy and Evolution”; Bio-complexity.org; Open Access; volume 2013, Issue 2, p1-5.