This is the end of the chicken and egg paradox

The scientists believe that the theories of Darwin and Mark coexist, and even complement each other. 

Some time ago, Prof. Yitzhak Pepper received a phone call from his brother: "You are a scientist, so maybe you can help in an argument I had with friends: which came first, the egg or the chicken?" This conversation led to a collaboration between Prof. Pepper, from the Department of Molecular Genetics at the Weizmann Institute of Science, and Dr. Oded Ravavi from Tel Aviv University.

In the article published by the two in the scientific journal Biology Direct, they claim that biologically, the eternal question - which comes first: the egg or the chicken - is not a paradox at all. And not only that, but it can even be used as a parable illustrating the gap between two versions of the theory of evolution: Lamarck's version and Darwin's version.

At the beginning of the 19th century, the French naturalist Jean-Baptiste Lamarck argued that the diversity of species in nature was created as a result of the transmission of acquired traits through heredity. According to his theory of evolution, living beings are subject to environmental influences that cause them to change, in order to adapt to the environment, and these acquired changes are transmitted to their offspring through the egg or sperm. In other words, the chicken (which adapted to the environment and changed itself) preceded the egg. On the other hand, according to the modern version of evolution, which developed from Darwin's theory, the new species are created following genetic mutations that occur in the egg or sperm - and only then are they tested according to their suitability to the environment; That is, according to this view, the egg preceded the chicken.

Since Darwin's concept is much more widespread in nature, in most cases the egg precedes the chicken (at least in terms of perception). But if Lamarckian evolution also takes place in nature, then in some cases, the chicken is the one that precedes the egg.

For about 200 years, the perception was widespread that Lamarck was wrong, but recently scientists began to discover that there are cases in which the concept he presented was still valid; That is, there are cases where the acquired changes are indeed inherited. Prof. Pepper recently wrote another article, published in the scientific journal Cell, in which he proposed - together with research student Idan Fromkin, and with former research student Dr. Avihu Yona, currently a postdoctoral researcher at the Massachusetts Institute of Technology (MIT) - A series of possible explanations for how evolution occurs according to Lamarck's concept - on the molecular level. The scientists maintain that when changes occur over time as a response to new environmental pressures, evolution acts as a kind of relay race, where at each stage of the process the "stick" is "passed" to the next one, thus accelerating the transition to the next stage.

The scientists propose to represent the types of adaptation of the living creature to environmental conditions according to the time span in which they exist: starting with short-term changes that do not affect the DNA at all, and ending with long-term adaptation, which changes the genetic load. Among the short-term changes are those that affect gene expression, but do not change the DNA sequence. This happens, for example, when in response to being at a high topographical height, the body produces more red blood cells that allow it to deal with a lack of oxygen. If harsh conditions persist for a long time, the environmental adaptation goes up a notch, to the epigenetic level - where, for example, changes in DNA occur that do not affect the genetic sequence. But in the end, if the harsh conditions continue to exist for a very long time, mutations may occur - that is, a change in the DNA sequence itself. In this way, just as Lemark claimed, the parents can pass on to their offspring the changes that occurred in their bodies during their lifetime, through changes in the genetic load of the egg and sperm cells.

Prof. Pepper and his research partners believe that the evolutionary messenger race developed because it allowed living creatures to quickly adapt to new conditions. But it is possible that the same mechanism is also used by cancer cells. It is known, for example, that these cells often contain extra copies of chromosomes. This phenomenon may develop in cancer cells as a kind of "messenger" in the messenger race: it increases the number of genes that contribute to the development of cancer, and spurs the formation of mutations that help the tumor develop faster.

in the article they published

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