Developmental Biology Quotes

Our work on C. elegans emphasized the benefits of sharing large amounts of information. We took a global approach to discover the mechanisms that led to the development of the worm.

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.

As with most animal eggs, the early events of amphibian development are largely independent of the environment, and the processes leading to cell differentiation must involve a redistribution and interaction of constituents already present in the fertilized egg.

Suppose that there's a gene that makes you gay if you were bottle-fed but that has some completely different effect if you were breast-fed. So in the days before bottles were invented that gene would not have manifested itself as gay behavior, but now that bottles are common it can do so.

The fallacy of genetic determinism is to suppose that the genes "make' the organism. It is a basic principle of developmental biology that organisms undergo a continuous development from conception to death, a development that is the unique consequence of the interaction of the genes in their cells, the temporal sequence of environments through which the organisms pass, and random cellular processes that determine the life, death, and transformation of cells. As a result, even the fingerprints of identical twins are not identical. Their temperaments, mental processes, abilities, life choices, disease histories, and death certainly differ despite the determined efforts of many parents to enforce as great a similarity as possible.

It will be in the convergence of evolutionary biology, developmental biology and cancer biology that the answer to cancer will lie. Nor will this confluence be a one-way street.

We can now determine, easily and relatively cheaply, the detailed chemical architecture of genes ; and we can trace the products of these genes ( enzymes and proteins ) as they influence the course of embryology . In so doing we have made the astounding discovery that all complex animal phyla - arthropods and vertebrates in particular - have retained, despite their half-billion years of evolutionary independence, an extensive set of common genetic blueprints for building bodies.

Cartoons are like fruit flies. Biologists use fruit flies because their large chromosomes and short life cycle make them ideal for studying hereditary changes.

For my part, I have worked all my life with eggs and embryos of frogs. Compared to other small animals, these have figured prominently in the world of literature.

Ontogeny re-capitulates phylogeny.

If a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may, in the course of untold millions of years, give origin to the human race.

as to fix the moment that the embryo becomes an animal.

Man is developed from an ovule, about 125th of an inch in diameter, which differs in no respect from the ovules of other animals.

A mutation can create an alternative form of a phenomenon - a phenotype or trait - and we can learn a lot by seeing this alternative state. Once I saw a mouse with no eyelids. It simply had a membrane over the eyes. I found it fascinating that there is a single gene required for eyelids to develop.

The three of us have worked on the development of the small and totally harmless fruit fly, Drosophila. This animal has been extremely cooperative in our hands - and has revealed to us some of its innermost secrets and tricks for developing from a single celled egg to a complex living being of great beauty and harmony. ... None of us expected that our work would be so successful or that our findings would ever have relevance to medicine.

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.

Heredity proposes and development disposes.

If the germ plasm wants to swim in the ocean, it makes itself a fish; if the germ plasm wants to fly in the air, it makes itself a bird. If it wants to go to Harvard, it makes itself a man. The strangest thing of all is that the germ plasm that we carry around within us has done all those things. There was a time, hundreds of millions of years ago, when it was making fish. Then ... amphibia ... reptiles ... mammals, and now it's making men.

If we possessed a thorough knowledge of all the parts of the seed of any animal (e.g. man), we could from that alone, be reasons entirely mathematical and certain, deduce the whole conformation and figure of each of its members, and, conversely if we knew several peculiarities of this conformation, we would from those deduce the nature of its seed.

Within six months of starting my Ph.D. work in 1956, I had already obtained feeding tadpoles derived from transplanted nuclei of embryonic cells.

I established the opposite view, that this history of the embryo (ontogeny) must be completed by a second, equally valuable, and closely connected branch of thought - the history of race (phylogeny). 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... 'ontogenesis is a brief and rapid recapitulation of phylogenesis, determined by the physiological functions of heredity (generation) and adaptation (maintenance).

A key issue in developmental biology at that time was the problem of how cells underwent differentiation, with most workers concentrating on explanations in terms of changes in enzyme and gene regulation.

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.

Owing to the imperfection of language the offspring is termed a new animal, but it is in truth a branch or elongation of the parent; since a part of the embryon-animal is, or was, a part of the parent; and therefore in strict language it cannot be said to be entirely new at the time of its production; and therefore it may retain some of the habits of the parent-system. (1794)

There is no gene "for" such unambiguous bits of morphology as your left kneecap or your fingernail. [...] Hundreds of genes contribute to the building of most body parts and their action is channeled through a kaleidoscopic series of environmental influences: embryonic and postnatal, internal and external. Parts are not translated genes, and selection doesn't even work directly on parts.