What makes a rhinoceros look like a rhinoceros, or a petunia like a petunia? Understanding the basis of the generation of the forms, patterns, or shapes of complex organisms is a principal subject of biologist Gerald Edelman ' s stimulating book Topobiology, which explores the links among the development, evolution, form, and function of organisms.

In older scientific language, one could say that Edelman has brought a new dimension to morphology, the study of the form and shape of animate and plants, and to histology, the study of the minute structure of tissues. The major thrust of his book te what he calls a morphoregulatory hypothesis, which can be described as the outline of a molecular basis for the formation of pattern, involving three types of genes. In the morphoregulatory sequence, morphoregulatory genes control the production of molecules that cause the formation of clusters of cells. When the cell dusters begin to communicate, they activate another type (selector genes) that then select and switch on a third type of gene (historegulatory genes).

In the organisms they have studied, Edelman and his colleagues have found cell adhesion molecules (resulting from morphoregulatory gene action) that are attached to the surface of different cells and link them in clusters. These molecules can appear at different times in the development of a multicellular system, and at various specific sites on the cells. Furthermore, their chemical structure can vary. This tremendous variation allows a great flexibility in the kinds of linkages the molecules effect.

A second class of adhesion molecules plays a comparable role In attaching cells to the developing scaffolding of filaments that lie outside cells. Also of particular interest to researchers are what are called cell Junction molecules, composed of clusters of proteins providing small channels from the inside of one cell to the Inside of another. These three types of molecules facilitate a kind of conversation among eels that determines the course of development of organisms. It has been possible to demonstrate how Important these molecules are by treating tissues with agents that block their functions, thus effectively and drastically changing the organism ' s development.

The following is based on an article published in 2012.

Most linguists believe proto-Indo-European, the ancestor of all Indo-European

languages, was the language of chariot-driving pastoralists who spread through

Eurasia from steppes north of the Black Sea about 4,000 years ago. But a

competing theory is that proto-Indo-European was spoken by farmers in Anatolia

(Asia Minor) about 9,000 years ago, and spread from there along with agriculture.

To evaluate these hypotheses, researchers statistically compared IndoEuropean languages’ vocabularies. Languages with more similar vocabularies are

probably more closely related, sharing more recent common ancestors.

Combining the vocabulary statistics with the known dates when certain languages

split, and with their known geographical ranges, a computer calculated the most

likely relationships among all Indo-European languages and concluded that protoIndo-European probably originated in Anatolia 9,000 years ago.

Disputing this conclusion, skeptics argue that most Indo-European languages

are similar in their words pertaining to chariots and wagons, suggesting protoIndo-European split into daughter languages only after chariots and wagons were

invented. No archaeological evidence indicates that chariots and wagons existed

before 5,500 years ago. Furthermore, proto-Indo-European had words for " horse "

and " bee " and lent many words to proto-Uralic, the mother language of Finnish

and Hungarian. The steppes north of the Black Sea were far closer than Anatolia

to areas where proto-Uralic was spoken, and had more abundant wild horses and

bees.