Ernst Haeckel Quotes

It is now firmly established that ontogeny does not repeat phylogeny

Man's body had a different shape in the past from that of the present, and from that which it will have in the future. During involution it was approximately spherical, as it still is during ante-natal life, because the intra-uterine development is a recapitulation of past stages of evolution.

Phylogeny and ontogeny are, therefore, the two coordinated branches of morphology. Phylogeny is the developmental history [Entwickelungsgeschichte] of the abstract, genealogical individual; ontogeny, on the other hand, is the developmental history of the concrete, morphological individual.

I have devoted my whole life to the study of Nature, and yet a single sentence may express all that I have done. I have shown that there is a correspondence between the succession of Fishes in geological times and the different stages of their growth in the egg,-this is all. It chanced to be a result that was found to apply to other groups and has led to other conclusions of a like nature.

Ontogeny re-capitulates phylogeny.

Biology is far from understanding exactly how a single cell develops into a baby, but research suggests that human development can ultimately be explained in terms of biochemistry and molecular biology. Most scientists would make a similar statement about evolution.

Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation.

Child psychology and animal psychology are of relatively slight importance, as compared with the sciences which deal with the corresponding physiological problems of ontogeny and phylogeny.

Embryology reveals surprising similarities between early embryos of seemingly quite different animals. And it also shows that some structures that may look very different later on have fundamental similarities in the way they form.

I'm here as a product of process of evolution, which doesn't make very many exceptions. And which rates life relatively cheaply.

Evolution isn't true, because if we evolved from monkeys, how can they still be here?

The concept of evolution postulates that living organisms have common roots, and in turn, the existence of common features is powerful support for the concept of evolution.

Evolution is a theory, and it's a theory that you can test. We've tested evolution in many ways. You can't present good evidence that says evolution is not a fact.

Where do we say that a cell became a blade of grass, which became a starfish, which became a cat, which became a donkey, which became a human being? There's a real lack of evidence from change from actual species to a different type of species.

It seems to me that for Darwin the pulsing of evolutionary rates was a strictly vertical phenomenon.

My prime interests are in evolution and development. I use the cellular slime molds as a tool to seek an understanding of those twin disciplines.

All mammals undergo a certain degree of diversification. Darwin knew that. When he drew a family tree, it had many branches on it.

Evolutionary biologists are not content merely to explain how variation occurs within limits, however. They aspire to answer a much broader question-which is how complex organisms like birds, and flowers, and human beings came into existence in the first place.

Biology will relate every human gene to the genes of other animals and bacteria, to this great chain of being.

Progressively thinking biologists, both in our country and abroad, saw in Darwinism the only right road to the further development of scientific biology.

If you ask most atheists if the theory of evolution has anything to do with a belief, however, they will tell you that it doesn't. It's not something that has to be believed. It is a 'fact.'

We need to separate the process of evolution - which is, indeed, a self-serving process - and the actual motivations of animals.

It is difficult to imagine evolution in alien planets operating in any manner other than Darwinian.

The theory of undirected evolution is already dead, but the work of science continues.

Fresh knowledge leads to recognition of the theory of evolution as more than just a hypothesis.