Brilliant Blunders: From Darwin to Einstein - Colossal Mistakes by Great Scientists That Changed Our Understanding of Life and the Universe (9 page)

In other words, inherited variation, and no blending at all. Moreover, Mendel tried several times to create variations in plants by removing them from their natural habitat to his garden at the monastery. When this failed to produce any change, Mendel told his friend Gustav von Niessl, “This much already seems clear to me, that nature does not modify species in any such way, so some other force must be at work.” Mendel therefore accepted at least some parts of the theory of evolution. This, however, raises another intriguing question: If Mendel agreed with Darwin’s concepts, and maybe even recognized the importance of his own results for evolution, why didn’t he mention Darwin by name in his writings? To answer this question we have to understand Mendel’s special historical circumstances. On September 14, 1852, the Austrian Emperor Francis Joseph I empowered Prince-Bishop Rauscher to act as his representative in drawing up a concordat with the Vatican. This concordat was signed in 1855, and in reaction to the winds of change in Europe in 1848, it contained strict regulations such as: “All school instruction of Catholic children must be in accordance with the teachings of the Catholic Church . . . The bishops have the right to condemn books injurious to religion and morals, and to forbid Catholics reading them.”

As a result of these restrictions, for instance, the paleontologist Antonén Fri
was not even allowed to lecture in Prague,
Czechoslovakia, on his impressions from a scientific meeting in Oxford in 1860 in which Huxley presented Darwin’s theory.
Although the Vatican itself delayed official pronouncements on Darwin’s theory for many decades, a council of German Catholic bishops did state in 1860: “Our first parents were formed immediately by God, therefore we declare that the opinion of those who do not fear to assert that this human being . . . emerged finally from the spontaneous continuous change of imperfect nature to the more perfect, is clearly opposed to Sacred Scripture and to the Faith.” In this rather oppressive atmosphere, Mendel, who was ordained a priest in 1847 and elected abbot of the monastery in 1868, probably did not think it prudent to express any explicit support for Darwin’s ideas.

We may still wonder what might have happened had Darwin actually read Mendel’s paper before November 21, 1866, when he completed his chapter on the ill-conceived pangenesis. Of course, we shall never know, but my guess is that nothing would have changed. Darwin was neither ready to think in terms of variation affecting just one part of an organism and not the others, nor was his mathematical ability sufficient to follow and fully appreciate Mendel’s probabilistic approach. To develop a specific, universal mechanism from a few isolated cases of a 3:1 ratio in the transmission of some properties of a particular plant was not Darwin’s forte. Moreover, Darwin’s stubborn defense of his theory of pangenesis demonstrates that at that point in his life, he may have been afflicted with what modern psychologists refer to as
the
illusion of confidence:
a common state in which people overestimate their abilities. While this principle generally applies to people who are unskilled but unaware of it, it can affect everybody at some level. For instance, studies show that most chess players think that they can play much better than their formal ranking implies. If Darwin indeed had the illusion of confidence, it would be quite ironic, since it was Darwin himself who once observed insightfully that “ignorance more frequently begets confidence than does knowledge.”

The complexities of developing a quantitative approach to the phenomena of variation and rate of
survival, and the complete integration of Darwinian selection and Mendelian genetics, took about seventy years to resolve. Initially, in the years following the 1900 rediscovery of Mendel’s pioneering 1865 paper, Mendel’s laws of heredity were even thought to be
opposed
to Darwinism. Geneticists argued that mutations—the only acceptable form of heritable variation—were abrupt and ready-made rather than gradually selectionist. This opposition subsided by the 1920s, following a number of seminal research projects. First, breeding experiments with the
Drosophila
fruit fly by biologist Thomas Hunt Morgan and his group demonstrated unambiguously that Mendel’s principles were universal. Second, the geneticist William Ernest Castle was able to show that he could produce inherited change by the action of selection on small variations in traits in a population of rats. Finally, the English geneticist Cyril Dean Darlington discovered the actual mechanics of chromosomal exchange of genetic material. All of these, and similar studies, showed that mutations occurred infrequently and most of the time were disadvantageous. On those rare occasions in which advantageous mutations arose, natural selection was identified as the only mechanism that could enable their propagation through the population. Biologists further came to understand that a large number of separately acting genes could affect a continuous variation in a characteristic. Darwin’s gradualism won the day, with natural selection acting on tiny differences to cause adaptation.

Darwin’s blunder and Jenkin’s criticism had another unexpected consequence: They essentially paved the way for the mathematical population genetics theory developed by Ronald Fisher, J. B. S. Haldane, and Sewall Wright. This was the work that provided the ultimate proof that Mendelian genetics and Darwinian selection were complementary and indispensable to each other. Given that Darwin got the fundamental fact of genetics wrong, it is absolutely amazing how much he got right.

The story of evolution is therefore not a simple narrative leading from myth to knowledge but a collection of diversions, blunders, and winding paths. Eventually, all of these intertwined threads converged into one conclusion: Understanding life requires
understanding very intricate chemical processes that involve some very complex molecules. We shall pick up this important thread again in chapters 6 and 7, when we’ll discuss the discovery of the molecular structure of proteins and of DNA.

•   •   •

I mentioned earlier the fact that Jenkin’s article raised a few other objections to Darwin’s theory of evolution. In particular, Jenkin relied on calculations by his friend and partner the famous physicist William Thomson (later Lord Kelvin), which appeared to show that the age of the Earth was much shorter than the vast expanses of time Darwin needed for his theory of evolution to work. The ensuing controversy provides us with fascinating insights not only into the differences between the methodologies in various branches of science but also (admittedly much more speculatively) into the operation of the human mind.

In the Beginning, God created Heaven and Earth . . . Which beginning of time, according to our chronology, fell upon the entrance of the night preceding the twenty-third day of October in the year of the Julian period, 710.

—JAMES USSHER, 1658

H
umans have been curious about the age of the Earth since recorded history. It is not often the case, after all, that one number—the Earth’s age—can have important implications for such diverse fields as theology, geology, biology, and astrophysics. Given that each one of these different disciplines has had its share of strongly opinionated individuals, we shouldn’t be too surprised to discover that by the nineteenth century, the attempts to estimate the Earth’s age had led to a number of bitter controversies.

The concept of a universal, linear time did not appear right away. In the ancient Hindu tradition, for instance, time had essentially no boundaries, and, like the ancient symbol of the ouroboros—the snake biting its own tail—the universe was assumed to undergo continuous cycles of destruction and regeneration. Nevertheless,
the Hindu sages of antiquity did come up with a rather “precise” number for the Earth’s age, which in 2013 was supposed to be 1,972,949,114 years. In the Western tradition, Plato and Aristotle were much more concerned with
why
and
how
the existing order of nature came about than with
when
, but even they toyed with the idea
of recurring cycles, in step with the heavenly motions. In the Christian world, on the other hand, a circular time was rejected in favor of a unique, nonrepeating straight line, leading from creation to the Last Judgment. In this religious context, determinations of the age of the Earth had been for centuries the exclusive province of theologians.
In one of the earliest estimates, Theophilus, the sixth bishop of Antioch, concluded in the year 169 that the world had been created some 5,698 years earlier. His motivation for calculating the age, he declared, was not “to furnish mere matter of much talk” but “to throw light upon the number of years from the foundation of the world.” While Theophilus did allow for a certain margin of error in his calculation, he did not think the error would exceed 200 years.

Many of the chronologists that followed him tended to simply add up time intervals between key biblical events, the scriptural ages at death of certain individuals, or the span of generations. Prominent
among these biblical scholars were John Lightfoot, the seventeenth-century vice chancellor of Cambridge University, and James Ussher, who became archbishop of Armagh in 1625. Even though the title of Lightfoot’s 1642 short book was carefully constructed to read
A Few, and New Observations, upon the Book of Genesis: The Most of Them Certain, the Rest Probable, All Harmless, Strange, and Rarely Heard of Before,
Lightfoot did not hesitate to pronounce that the creation of the first human—Adam—occurred precisely at nine o’clock in the morning! As for the date of the creation of the world, Lightfoot settled on 3928 BCE.

Ussher’s calculation was somewhat more sophisticated in that he complemented the biblical accounts by some astronomical and historical data. His punctilious conclusion: The world appeared on the evening before October 23, in the year 4004 BCE. This particular date became well known in the English-speaking world, since it was
added as a marginal note to the English Bible in 1701.

Naturally, the Christian view of time followed largely upon the heels of the Jewish tradition, which was also based mostly on a literal reading of the narrative in the book of Genesis. In the context of a divine drama in which the Jewish people were supposed to play the
principal role, having a history was clearly crucial. According to this heritage, the world was created some 5,773 years ago (as of 2013). Prophetically, one of the most influential Jewish scholars of the Middle Ages—Maimonides (Moshe ben Maimon)—advocated against a literal interpretation of the biblical text. As if anticipating what Galileo Galilei would say more than four centuries later, Maimonides argued that whenever accurate scientific findings are in conflict with the Scriptures, the biblical texts should be reinterpreted. The Dutch Jewish philosopher Baruch de Spinoza echoed the same sentiments:
“The knowledge of . . . nearly everything contained in Scripture, must be sought only from Scripture itself, just as the knowledge of nature is sought from nature itself.” In fact, Maimonides was not even the first to suggest that the passages in Genesis had been intended only allegorically. In the first century, the Hellenistic Jewish philosopher Philo Judaeus of Alexandria wrote presciently:

It would be a mark of great naïvety to think that the world was created either in six days, or indeed in time at all; for time is nothing but the sequence of days and nights, and these things are necessarily connected with the motion of the Sun above and below the Earth. But the Sun is a part of the heavens, so that time must be recognized as something posterior to the world. So it would be correct to say not that the world was created in time, but that time owed its existence to the world.

As we shall see in chapter 10, Philo’s last sentence conforms nicely to Einstein’s ideas in his theory of general relativity.