Historia Del Esperma

Reprod Dom Anim 47 (Suppl. 4), 2–6 (2012); doi: 10.1111/j.1439-0531.2012.02105.x
ISSN 0936-6768

An Amazing 10 Years: The Discovery of Egg and Sperm in the 17th Century
M Cobb
Faculty of Life Sciences, University of Manchester, Manchester, UK

Contents
The scientific identification of the key components of sexual
reproduction – eggs and sperm – took place during an
amazing decade ofdiscovery in the 1660s and 1670s. The
names of many of the people involved are now forgotten,
and yet their work, and the difficulties they faced and the
conflicts they endured, resonate strongly to the present day.
Despite this period of innovation, the respective roles of egg
and sperm remained unclear for another 170 years. Why did
this take so long? And what did people think before thesediscoveries? By tracing the contours of this major milestone
in human knowledge, we can also gain insight into our
current knowledge, and the boundaries we may be unwittingly trapped by.

Introduction
The 17th century discovery of the role of egg and sperm
in reproduction can be traced to two letters, written
7 years apart, each by a remarkable man who is largely
forgotten today. Those lettersheralded an amazing
decade of discovery that eventually shaped the way we
now understand life.
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In April 1665, Melchisedec Thevenot (c.1620–92), a
French patron of the sciences, wrote to his friend
Christiaan Huygens (1629–95), a Dutch mathematician
and astronomer: ‘We took the opportunity provided by
the cold of recent months and applied ourselves to
dissections and to investigating theGeneration of
´
animals’ (Thevenot 1665). The ‘we’ referred to two of
´
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Thevenot’s proteges, the Dutchman Jan Swammerdam
(1637–1680) and the Dane Niels Stenson (‘Steno’)
(1638–86). This was the start of a process of discussion,
dissection and experimentation that would soon lead
Swammerdam and Steno to the conclusion that all
animals – including humans – come from eggs.
The secondletter was sent 9 years later, in April 1674.
It was written by Henry Oldenburg (c.1615–77), the
German secretary of the Royal Society (Hall 2002) and
was sent to a Delft draper, Leeuwenhoek (1632–1723).
In the letter, Oldenburg asked Leeuwenhoek to use his
microscope to study semen, saliva, chyle, sweat and
other bodily fluids. With this inspiration, in 1677,
Leeuwenhoek would make one of themost stupendous
discoveries in the history of science: the observation of
spermatozoa.
To understand why these two letters were so important, we need to unlearn all that we know about
reproduction, beginning with that word. The term
‘reproduction’ was first introduced by Buffon in 1749
(Roger 1997). Up until then, people spoke about
‘generation’, and this was taken to include both howorganisms grow apparently from nothing, and how male
and female contributed to new life (Cole 1930).

Although the simple answer to the question ‘where
do babies come from?’ is fairly obvious – they come
out of the female vagina – arriving at an explanation of
how the baby got there in the first place proved quite
difficult (Cobb 2006a). It seems very likely that early
human populations did notknow that intercourse led
to babies. There are number of reasons for thinking
this. Firstly, how could they know? The link between
intercourse and pregnancy is not at all clear or
immediate – people can easily have intercourse without
the woman getting pregnant and the first signs of
pregnancy may not be seen for weeks after the act. This
surprising supposition is supported by the widespreadexistence of matrilineal communities in hunter-gatherer
societies, which suggests that men’s role in generation
was uncertain.
It is possible that the domestication of animals
provided the key. In all domesticated animals, mating
takes place only during oestrus (Potts and Short 1999).
Placing the animals together to allow mating would
have been an important step in domestication and in...