As human embryos develop they progress through stages that look like the many evolutionary ancestors of humans such as fish and reptiles. This development by the embryo is proof that humans evolved, and that they, and all modern land animals evolved from fish and reptiles.
The Facts Are .....
The Biogenetic Law (also known as The Embryonic Recapitulation Theory), popularized by Ernst Haeckel, states that the human embryo goes through various stages of development which show the features of its supposed evolutionary ancestors. Even though Haeckel admitted that he fraudulently altered his diagrams to fake this theory, many still believe it. American Scientist, Vol. 76, May-June, 1988 p:273
If humans evolved from apes, then the Biogenetic Law necessitates that there must be some ape-like characteristics displayed by the human embryo as it develops - eg. a hand-like grasping motion of the foot. A study of the development of the human embryo reveals that there is not the slightest hint of any climbing function displayed by the legs that would indicate that we descended from apes. At 6 weeks, the site of limb development can be seen. At 8 weeks the five folds that become toes can be seen. Early movements can be seen at 15 millimetres long, with the legs exhibiting actions of pushing and bracing. At 3 months, although the hand can make a fist and oppose the thumb, the feet are spread-eagled and never make any gripping motion. At three months the foot looks like that of a baby. At six months the hand can grip tightly, but the legs only kick. The only development that is observed is that consistent for an individual with upright posture and two-legged walking.
Creation Ex Nihilo, Vol. 13, No. 1, 1991 p:16-17
"The biogenetic law has become so deeply rooted in biological thought that it cannot be weeded out, in spite of its having been demonstrated to be wrong by numerous subsequent scholars". Written by Walter J. Bock (Department of Biological Science, Columbia University) in Science, Vol. 164, May 1969 p:684
Except for ‘diehard’ evolutionists, the Biogenetic Law is no longer used as proof of evolution.
Professor G.G. Simpson has referred to it as "the overgeneralized and much abused aphorism of the nineteenth century". G.G. Simpson "The Meaning of Evolution", (revised), Yale University Press, 1967 p:218; Science, Vol. 164, May, 1969
The idea of 'gill slits' in human embryos has been used for many years as 'proof' that we, and all other animals, evolved from fish. However, humans do not really have gill slits; their embryo have pharyngeal pouches. Fish have brachial apparatus which connects the inside of the pharynx to the outside, a feature missing in humans. The human embryonic pouches develop into important organs such as the thymus and parathyroid glands, showing that they are structures and not slits.. Jan Langman,
"Medical Embryology", [4th ed.] Williams & Wilkins: Baltimore, 1981
Stephen J. Gould, in his book "Ontogeny and Phylogeny" says that although he knows that human gill slits are now discredited as evolutionary remnants, it is a nice idea that has some substance to it.
Stephen J. Gould, "Ontogeny and Phylogeny"