Lectures on the Torah Reading

by the faculty of Bar-Ilan University

Ramat Gan, Israel

Parashat Noah

A project of Bar-Ilan University's Faculty of Jewish Studies, Paul and Helene Shulman Basic Jewish Studies Center, and the Office of the Campus Rabbi. Sponsored by Dr. Ruth Borchard of the Shoresh Charitable Fund (SCF). Published with assistance of the President's Fund for Torah and Science. Permission granted to reprint with appropriate credit.
Inquiries and comments to: Dr. Isaac Gottlieb, Department of Bible, gottlii@mail.biu.ac.il

Parashat Noah 5759/1998


Prof. Natan Aviezer

Dept. of Physics


One of the most difficult questions in the Book of Genesis relates to the extreme ages ascribed to the first 20 generations - from Adam to Abraham. Genesis speaks of people in this period who lived for more than 900 years, culminating in the record holder - Methuselah - who reached the unbelievable age of 969. How are we to understand such longevity? Anyone who has had close contact with the very elderly has observed that the human body literally deteriorates as one approaches the age of 100. Thus, the Biblical accounts of people who lived for many hundreds of years seem completely impossible.

There is yet another difficulty. After the time of the Exodus from Egypt, extreme longevity disappears and the life span of subsequent generations becomes normal by present-day standards - completely consistent with the traditional 120-year maximum life span. What happened to cause this dramatic decrease in longevity?

These are the questions to be addressed here. It will be shown that important recent scientific advances regarding the process of aging pave the way for understanding the nearly thousand-year life span of the early generations in Genesis, as well as the contemporary life span of those who lived after the time of the Exodus.


Until quite recently, no one really knew why human beings age. But within the last two decades, there have been enormous advances in our understanding. In fact, the study of aging has become the focus of such intense scientific effort that one of the leading authorities speaks of "a revolution in aging research."[1] The findings of this recent research have taken us by surprise, with the result that scientific journals aimed at the educated layman now abound with articles that describe these exciting discoveries. A few examples will illustrate the point.

In 1996, the cover of New Scientist declared: "Life at 200: Will We Always Grow Old?" and its article, dramatically entitled "Death of Old Age," began as follows:

We can live healthy lives well into our hundreds, researchers claim.[2]

In 1997, a news item in Scientific American was entitled "Immortality Gene Revealed," and it reported:

Two teams of scientists have cloned the gene for telomerase, known as the "holy grail" of aging research....Cells that produce telomerase are immortal.[3]

In 1992, Professor Michal Jazwinski, Director of the Center on Aging at Louisiana State University, a major figure in aging research, asserted that:

The maximum human life span might go as high as 400 years.[4]


Aging is one of the universal human experiences. Aging and death seem as natural as breathing, and just as inevitable. Long regarded as a mysterious aspect of life, recent scientific research has revolutionized our knowledge about the causes of aging.[5] As scientists continue to make breathtaking progress and gain new insights about the basic mechanisms responsible for aging, they develop the ability to intervene in the aging process and thereby to extend the human life span. This new-found knowledge strongly suggests that biomedical advances will eventually permit us to delay and even to eliminate many of the causes of aging and death.

The characteristics of aging are many: The body produces chemicals (free radicals) that destroy tissues by a process called oxidation; The immune system weakens and is no longer able to defend the body against disease; Structural proteins become altered, leading to rigidity of the heart muscle, lungs, ligaments and tendons; Cataracts form in the eyes; Certain cells (fibroblasts) lose their ability to divide (Hayflick limit). DNA molecules, which are vital for cellular replication, become damaged by mutations; Cancers develop as cells suddenly proliferate out of control. Hormonal changes occur that cause the gradual destruction of the bones (osteoporosis). Critical enzymes cease functioning, strokes attack the brain, Arthritis appears in the joints. Nerve cells in the brain degenerate (Alzheimer's disease), blood vessels lose their elasticity (arteriosclerosis) and cease to function properly, Parkinson's disease and diabetes develop; Memory declines.

It now appears that there is a common cause for this seemingly endless list of afflictions of age. Although still subject to some controversy, a scientific concensus is emerging that the root cause of all aging processes is genetic. According to Professor Caleb Finch of the Department of Neurobiology of Aging at the University of Southern California, "we are convinced that the rate of aging is under genetic control."[6] That is, the body does not wear itself out, as a car or washing machine finally wears out after years of faithful service. Rather, the human body contains certain genes (or lacks certain genes) that cause all the havoc listed above. In other words, we all suffer from "genetic defects." Therefore, if one could identify these defective genes and neutralize their effects (or introduce the "missing" genes) through genetic engineering, then the human life span could be extended, perhaps very considerably. This exciting possibility, discovered by scientists who study aging, is responsible for the recent dramatic pronouncements quoted above.

The idea that genes cause aging has recently received important support from the research work of Professor Mark Azbel, formerly at Moscow State University and now at Tel Aviv University. In a series of pioneering papers,[7] Professor Azbel has shown that the extensive mortality data for human beings can all be explained by assuming a genetic basis for aging and death.

this proves that there exists a genetically programmed probability to die at a given age.... that age may be genetically manipulated.[8]

Experiments that alter the genetic structure of laboratory specimens have already produced striking results. A small nematode worm (Caenorhabditis elegans) has about 13,000 genes. Professor Tom Johnson of the University of Colorado discovered that changing a single gene, aptly named age-1, doubles the maximum life span of this nematode.[9] Professor Michael Rose of the University of California has produced a new genetic strain of fruit flies (Drosophila melanogaster) that live almost twice as long as their standard laboratory-reared counterparts. Moreover, these "superior" flies are "more robust at every age....Even when they are old, many are stronger than ordinary young specimens."[10] Similarly, Professor Michal Jazwinski has identified several genes that prolong the life of brewer's yeast (Saccharomyces cerevisiae). Introducing the gene LAG-1 not only significantly extends the life span, but also "yeast cells that bear this gene maintain their youth longer."[11]

For those readers who find incredible the suggestion that genetically engineered living creatures could possess enormous life spans, we point out that there exist at present many animals that never appear to grow old. That is, their low mortality rate of youth persists without increasing throughout their life, their bodies do not exhibit any signs of aging, and they continue to bear offspring all their life. In other words, these animals remain biologically young for as long as they live. As Professor Leonard Hayflick of the University of California explains:

Some animals do not seem to age at all. If they do age, it occurs at such a slow rate that their aging has not been demonstrated. Non-aging animals experience a peak in their physiological functions at some point, but these functions do not seem to decline.... non-aging animals do not live forever because of accidents, disease and predation.[12]

Perhaps the most astounding data come from the field studies of the Scottish ornithologist George Dunnet who has spent a lifetime observing a colony of marine birds called fulmars (Fulmarus glacialis) on the Orkney Islands. He reports that:

Fulmars show no increase in mortality rate and no decline in female reproduction up to at least the age of 40 years. Certainly, no species of a similarly-sized mammal is known to maintain her fertility at a comparable age. Do these birds avoid aging altogether? We do not know.[13]

As of 1990, the Milwaukee zoo and the Moscow zoo each possessed an Andean condor (Vultur gryphus) this is nearly 80 years old, continues to lay eggs, and shows no signs at all of aging.[14] Studies of turtles and certain fish yield similar results:

One specimen of Marion's tortoise (Geochelone gigantea) died accidentally at 150 years of age in a British fort on Mauritius. Studies in progress on other turtle species suggest that they remain fertile throughout their life and that their mortality rate remains low.... The longevity records for fish are held by rock fish and sturgeon (Acipenser fulvescens), which reach 150 years of age, as confirmed by the number of rings on their scales. The very old individuals of rock fish (Sebates aleutianus) studied by Bruce Leaman of the Pacific Biological Station of Fisheries, produced normal egg masses and showed no sign of the usual tumors and other pathological lesions found in mammals at advanced ages.[15]

The data for plants (primarily trees) are no less astonishing.

Many species of hardwoods and conifers live for 1000 years or more, producing seed year after year. The greatest individual life spans are found in the bristlecone pine (Pinus aristata). The ages of some of these trees, determined from annual growth rings, exceeds 4500 years. There is no hint of senescence [aging] in these long-lived trees... Certain plants propagate by runners that are part of the same individual plant. Propagating in this manner, these plants seem to be potentially immortal... Wine lovers will be interested to read that some Cabernet Sauvignon grape vines have produced grapes for at least 800 years.[16]


In the light of the above discussion, it should not be too difficult to imagine a world in which human beings do not age. This does not mean that no one will ever die. Our lives would still be cut short by usual hazards of traffic accidents, virulent diseases and violent crime. But the rate at which we die -the mortality rate - would not increase with age. For example, the chances of dying in a car accident are about the same at age 60 as they are at age 20. The safest age for human beings is 10-15 years. The period of dangerous childhood diseases is past and the infirmities of old age have not yet begun. In the United States and Western Europe, the mortality rate - defined as the chances of dying within one year - of a 10-year-old boy is about 0.05%; that is, only 1 in 2000 male youngsters will die within a year. (Young girls do somewhat better.) This is the minimum mortality rate observed for male human beings. By contrast, the mortality rate for 100-year-olds is 50%; half the centenarians will not survive the year.

What can one say about the human life span in a world without aging? If human beings did not age, then everyone would remain forever young, and the minimum mortality rate - that of a 10-year-old child - would persist for one's entire life. Professor Caleb Finch has shown[17] that under these circumstances, 95% of the population would reach the age of 100 and the average life span would be about 1300 years. Moreover, chronologically extremely old - but biologically still young - men and women would be able to sire children and give birth throughout their thousand-year lives. This is how human society would appear if one could eliminate all the genetic defects that cause aging.


Having examined the recent scientific advances regarding aging, we return to the account in Genesis of the extreme longevity of the early generations. It is very useful to display the life spans for the first 27 generations in a figure, which is presented on the following page. From this figure, it is clear that there is a marked difference between the life spans before Noah and those after Noah. Up to and including Noah, the life spans are nearly all the same (about 900-950 years), except for Enoch, who is explicitly described in Genesis as having died young and may therefore be removed from consideration. After Noah, however, the life span decreases rapidly, falling steadily from 959 years for Noah (10th generation) to reach the "traditional" value of 120 years by the time of Moses (26th generation).

1. The 900-year life spans up to the time of Noah

Consider the following scenario. When Adam and Eve were in the Garden of Eden, they were destined to live forever. We propose that this immortality was the result of Adam and Eve not possessing any of the "genetic defects" that nowadays cause aging (as discussed previously). Moreover, Adam and Eve were not subject to the non-genetic causes of mortality, which are unrelated to aging. In the Garden of Eden, there presumably were no traffic accidents, no virulent diseases, and no violent crime. Therefore, it follows that Adam and Eve would live forever.

When Adam and Eve ate the "forbidden fruit," they were forced to leave the Garden of Eden and enter the outside world. Of course, once they were outside the Garden of Eden, they became subject to the usual non-genetic causes of death that afflict us all (accidents, diseases, etc.), and hence they became mortal. Indeed, this is precisely what G-d meant when He told Adam and Eve that "on the day that you eat of the tree of knowledge, you will die" (Genesis 2:17). Not that Adam and Eve would die on that day, but rather, they would become mortal - subject to dying - on that day.

The key point of our proposal is that even after leaving the Garden of Eden, Adam and Eve still did not have any genetic defects of aging, and therefore, they did not age. This explains both their extreme longevity (930 years for Adam), as well as their ability to bear children at such an advanced age.

We have already seen that in the absence of aging, the average human life span would be about 1300 years. Thus, we really have to explain why the early Biblical life spans were so short! In this regard, we note that there is no reason why the present-day non-aging life span should be exactly the same as it was in early Biblical times. Presumably, back then they had fewer traffic accidents, but they also did not have the antibiotics we possess today to cure deadly diseases. Indeed, the difference of only 40% between the contemporary non-aging life span (about 1300 years) and the early Biblical life span (about 900-950 years) should be viewed as remarkably good agreement.

This approach also explains the advanced ages of childbearing of the early generations in Genesis. Methuselah and Lamech were nearly 200 years old when they sired children, and it is explicitly mentioned that they had additional children even later in life. Similarly, Noah was 500 years old when his sons were born. Moreover, at the age of 600 years (Genesis 7:6), Noah was placed in complete charge of the complicated enterprise of building and outfitting the Ark, hardly a task that could be assigned to a doddering old man. Thus, it is clear that Noah not only lived extremely long, but he also remained biologically young throughout his long life.

We have already seen that the ability to bear offspring until the end of life is characteristic of those animals and plants that have unusually long life spans. Recall the 80-year-old Andean condors, the 150-year-old rock fish, and the 1000-year-old conifers, that we had discussed previously. Moreover, it is observed that long life spans are also associated with the lack of any of the other usual signs of aging. Thus, a consistent picture emerges between the unusually long life spans of the early generations in Genesis, their ability to sire children at an advanced age, and their lack of any signs of aging throughout their long life.

There is another point to be made. Recent discoveries have shown that it is probably not possible for a human being to be completely free of "genetic defects," for the following reason. Sometimes, the same gene that is necessary for one important bodily function early in life, may be harmful to the body later in life. This is called antagonistic pleiotropy,[18] an important concept introduced into the study of aging by Professor George Williams of the State University of New York at Stony Brook. Thus, it is reasonable to assume that the early generations in Genesis did have a very small number of genes that produced some signs of aging. These few genes would eventually lead to death at some advanced age (say, 900 years), far beyond the contemporary life span (about 80 years) but still considerably shorter than the enormous life span (about 1300 years) predicted in the absence of any aging genes at all. Moreover, this approach also explains why the life spans of almost all the early generations were so similar. (Of the nine persons mentioned[19] in Genesis who lived before the time of Noah, all but one had a life span in the restricted range of 895-969 years.) Genes for aging can be shown to produce such an effect.

2. The rapid decrease in life span after the time of Noah

Genesis records three important differences between the generations that lived immediately after the time of Noah (10th generation) and those that lived earlier. These include the following:

(i) As the figure shows, the life span decreased rapidly after Noah (959 years), with no one living for more than 240 years after Eber (14th generation). After the time of Moses (26th generation), there is no instance recorded in the Bible of anyone living significantly longer than 120 years, which remains to this day the maximum human life span.

(ii) People no longer sired children at an advanced age. After Shem (11th generation), the age of having children dropped to the 30s, just like today. Indeed, when Abraham and Sarah (20th generation) become the parents of Isaac at ages 100 and 90 years, respectively, Genesis describes the event as miraculous.

(iii) For the first time, people are described in Genesis as becoming old and infirm. Aging in later life is a characteristic feature of the Patriarchs and Matriarchs (20th to 22nd generations).

This applies to Abraham and Sarah (Genesis 18:11-13), to Isaac (27:1-2), and to Jacob (48:10).

It is clear that something happened at the time of Noah to cause these three important changes in the later generations, all of which are associated with aging. An examination of the Biblical text reveals that this event is stated explicitly. In Genesis 6:3, we are told that G-d was extremely dissatisfied with the corrupt behavior of people at the time of Noah, and therefore, He decreed that the maximum human life span will be reduced to 120 years ("therefore man's days shall be one hundred and twenty years").[20] However, we note that the maximum human life span did not, in fact, immediately decrease to 120 years. A full ten generations after this divine pronouncement, Abraham still lived to the age of 175, with similar life spans for the other Patriarchs.

In the light of our earlier scientific discussion of aging, we propose that the divine pronouncement of Genesis 6:3 can be understood as meaning that at the time of Noah, the genes for aging were introduced into the human gene pool. It would, of course, take a number of generations for these "aging genes" to propagate throughout the entire human population. This would explain why another 16 generations were to pass (from the time of Noah until the time of Moses) until the maximum life span finally became reduced to the divinely-decreed value of 120 years, with the human life span decreasing steadily during this transition period (from 959 years for Noah to 120 years for Moses). This proposal also accounts for the fact that after the time of Shem (Noah's son), there are no more (non-miraculous) instances in Genesis of people having children at an advanced age. Finally, this also explains why the usual infirmities of old age were exhibited by the Patriarchs, whereas they were absent in the earlier generations.

In conclusion, the recent dramatic scientific discoveries regarding aging provide the basis for a comprehensive explanation of all aspects of the extreme longevity of the early generations described in Genesis.


1. S. M. Jazwinski, Science, 5 July 1996, vol. 273, p. 54.

2. D. Concar, New Scientist, 22 June 1996, p. 24.

3. "News In Brief", Scientific American, October 1997, p. 14.

4. R. L. Rusting, Scientific American, December 1992, p. 95.

5. For excellent and authoritative popular accounts of the many recent advances in aging, see R. E. Ricklefs and C. E. Finch, Aging (New York: Scientific American Library, 1995) and L. Hayflick, How and Why We Age (New York: Ballantine Books, 1994). For an encyclopedic treatment, see C. E. Finch, Longevity, Senescence, and the Genome (Chicago: University of Chicago Press, 1990).

6. R. E. Ricklefs and C. E. Finch, Aging (New York: Scientific American Library, 1995), p. 176.

7. M. Ya. Azbel, Proceedings of the National Academy of Sciences (USA), 1994, vol. 91, pp. 12453-12457; Proceedings of the Royal Society of London, 1996, vol 263B, pp. 1449-1454; Physics Reports, 1997, vol. 288, pp. 545-574; Physica A, 1998, vol. 249, pp. 472-481.

8. M. Ya. Azbel, Physics Reports, 1997, vol. 288, p. 545.

9. T. E. Johnson, Genetics, 1988, vol. 118. pp. 75-86.

10. R. L. Rusting, Scientific American, December 1992, p. 87.

11. Rusting, p. 91.

12. L. Hayflick, How and Why We Age (New York: Ballantine Books, 1994), pp. 21-22.

13. G. M. Dunnet, in Reproductive Success: Studies of Individual Variation in Contrasting Breeding Systems, ed. T. H. Clutton-Brock (Chicago: University of Chicago Press, 1988), p. 268.

14. C. E. Finch, Longevity, Senescence, and the Genome (Chicago: University of Chicago Press, 1990), p. 148.

15. R. E. Ricklefs and C. E. Finch, Aging (New York: Scientific American Library, 1995), pp. 8, 10.

16. Ricklefs and Finch, p. 13.

17. Ricklefs and Finch, p. 2.

18. G. C. Williams, Evolution, 1957, vol. 11, pp. 398-411.

19. Recall that we have eliminated Enoch from consideration because it is explicitly stated in Genesis that he died young.

20. This verse is often interpreted in a non-literal midrashic sense (see, for example, Rashi). However, in the present analysis, we concentrate on the literal meaning of the Genesis text.