The Universe Within (15 page)

Clues to the relevance of oxygen levels to animal life came from the observations made as early as 1919 by one of the fathers of the field of
physiology.
Schack August Steenberg Krogh (1874–1949) was fascinated by physical and chemical laws that govern the physiology of animals. One of them he found by looking at the correlations between the properties of water and the creatures that live in it. In simple marine creatures, ones with no elaborate circulatory or digestive systems, body size is limited by the amount of oxygen in the water. In oxygen-restricted environments, being big is physiologically impossible, so these
creatures are restricted to small
sizes. With enhanced levels of
oxygen comes an increase in the sizes that creatures can attain.

Preston
Cloud inferred that rising levels of oxygen—and the new energetic landscape it brought—defined a new realm of possibilities for ancient life. Oxygen lifted the lid on big: it fueled the push from microscopic creatures living in a world dominated by inter
molecular forces to a planet with ever-bigger species with new kinds of bodies.

Oxygen also created an entire new world of
danger.

Every change is a double-edged sword. The chemistry that makes oxygen so efficient at generating energy can turn it into a poison. A great receptor for
electrons from other atoms, oxygen generates energy while it forms new compounds. Unchecked, these molecules can disrupt
cells and damage
DNA. A number of theories of disease and aging are based on these properties of oxygen. Every time you take an antioxidant like vitamin C, you are trying to fight the effects of these kinds of oxygen-containing molecules.

But there is a deeper challenge to being a big creature living in an oxygen-rich world. A human body is composed of an enormous number of parts—two trillion cells, thirty thousand genes—that function as a whole: organs, tissues, and genes work together to ensure the integrity of each individual. The balance among parts is defined by the ways our different cells attach to each other, communicate, and interact with the molecules that lie between them. When we’re healthy, each organ of our bodies “knows” how to behave; its cells continually divide and die, yet it remains roughly the same size and shape. Each eye is about the same size, as are each thumb and big toe. Our spleen and liver have their right sizes. This intricate harmony of parts is necessary for us to function as many-celled individuals.

Insights into this balance came from odd
flies: members of a
laboratory at Johns Hopkins noticed some flies in their breeding colony that had eyes way too large for their heads—five times bigger than normal. Being geneticists, they were well prepared for analyzing the genes. They isolated the
DNA of the gene, traced its molecular activity, and discovered that it lies in a chain of molecular reactions that tell cells to stop growing.
Controlling growth, either through slowing down the division of cells or by managing their death, is the centerpiece of building a harmonious large body.

Using their knowledge of the structure of the fly gene, the Hopkins team was able to trace it to mice and people. Not only is a version of the fly gene present in the
genome of mammals, but mutations bring about organs of new
sizes. The gene appears to behave in generally similar ways in flies, mice, and people, working as part of a molecular chain reaction to define a balance among parts. In mice, a mutation can bring about a liver five times the normal size.

But mutations of the gene also have another consequence. When cells lose their cues to stop dividing or dying at the right time, they can form deadly malignancies. The genes that define the ways our bodies get big also form the basis to destroy them.

Preston
Cloud and others who followed him saw the harmony between living systems and planetary ones. The interplay between living things and their planet led to increasing levels of oxygen in the atmosphere. Oxygen, in turn, changed the world by allowing for the origin of big creatures with many cells. Life changes Earth, Earth changes life, and those of us walking the planet today carry the consequences within.

E
arth of 530 million years ago was still far from being a place we’d recognize as home. Breathing would have been like summiting Mount Everest without an oxygen tank;
atmospheric oxygen levels, while having increased substantially since the early days of the planet, remained only a fraction of those today.
Water was the happening place for
life: new kinds of soft-bodied animals swam in the oceans. Land, by contrast, was a barren void lacking any sort of plant cover or soil. If you managed a hike on this strange landscape, you could have walked from what is today Boston to Australia without ever seeing ocean.

The modern world came about through changes to
rock,
air, water, and
life. But, as the story of
oxygen reveals, these constituents do not exist in isolation from one another.
Earth’s history is the product of interlinked changes to the planet and the creatures on it. Learning to see the deep meaning of these grand connections, and the roots for one of the greatest scientific revolutions of all time, begins with one of the most seemingly mundane exercises of all—making
maps. Maps tell us where we are and what our world looks like, and, when we use them in the fullness of geological time, expose the links that exist among oceans, mountains, and the organs inside our own bodies.

Children, as every parent knows, are driven to find patterns in the world around them. Take a globe or a map, and show it to kids about seven years old. Ask them to describe what they see, not the names of the regions, but the shapes of various continents, islands, and oceans. Almost invariably, kids will point out that parts look as if they fit together. The east coast of
South America and the west coast of
Africa seem to match perfectly.

In some quarters, even as recently as forty years ago, this simple observation reflected complete heresy. In junior high school, I had a teacher who lectured class on the pseudoscientific ideas that were in vogue in the late 1960s. One was the notion that the Egyptian pyramids, the Nazca lines of Peru, and the statues on Easter Island were influenced by the work of space aliens who would regularly visit our planet. Like most of the students, I thought the space alien idea great—it was on TV, after all. My teacher’s intent was to show that while these kinds of ideas may have been fun and fantastic stories, they could not be tested in any meaningful way. He lumped these tales of science fiction with another called continental drift, the idea that the continents have moved over time. This lecture transpired in 1972. Little did my teacher know of a great revolution that had its start nearly 120 years before.

In 1856, the brothers
William and Henry Blanford arrived in
India to work in the famed
Talcher Coalfield. This field is still producing today, as part of
Mahanadi Coalfields Limited. While studying the layers of coal, the Blanfords, like all good geologists, looked above and below to see geological events surrounding its formation. One of the layers stood out; it was filled with huge, irregular
boulders—some even the size of a person. The mystery deepened when they looked closely at the buried boulders themselves: each had slashes and gashes on the surface. If found in the Alps or in the high Arctic, these features would have been taken as evidence of transport by huge
glaciers. But here, buried underneath layers of coal in equatorial India?

The boulder layer didn’t stop in India. Soon after the Blanfords’ discovery, geologists working in
South Africa discovered the same series of rocks: a coal bed and a layer of irregular and gashed boulders. Were there glaciers in South Africa and India at some point in the distant past? How did ice get to these places?

Eduard Suess (1831–1914) was born in London and, after moving to Vienna, developed a passion to understand the workings of Earth. After school, Suess rose through the ranks to become a leading academic and, later, city councilman for Vienna. There, he put his knowledge of geology to use for the common good by spearheading the development of an aqueduct to bring freshwater into the city from the surrounding mountains. This act is thought to have saved a large number of lives, since typhoid outbreaks from dirty water were common in the city beforehand.

Suess’s view of the importance of rocks was revealed in a speech he gave to an international congress of geology in 1903, when he described the work of a geologist in this way: “The stone which his hammer strikes is but the nearest lying piece of the planet,…the history of this stone is a fragment of the history of the planet, and … the history of the planet itself is only a very small part of the history of the great, wonderful and ever
changing Kosmos.” To Suess, each rock, properly interpreted, was a window into a world that stretches across the far reaches of space and time.

With this philosophy as a guide, rocks and
fossils took on new meaning. About a decade before the aqueduct proposal, Suess became interested in an enigmatic fossil with leaves shaped something like a cow’s tongue. The
plant, known as
Glossopteris
(Latin for “tongue leaves”), was a real mystery. As is typical with larger fossil plants, the whole organism is almost never found; individual leaves, branches, roots, and trunks are used to reconstruct it. This exercise is like putting a three-dimensional puzzle together from incomplete parts. By Suess’s time,
Glossopteris
was already known to be strange; it had a soft woody interior, making it like a conifer or fern, but it was unlike either in that it carried organs with seeds inside. Judging from the relative sizes of branches and leaves,
Glossopteris
occasionally rose ninety feet high and may have tapered toward the top, much like a Christmas tree.

Suess noticed that the really astonishing fact of
Glossopteris
lay not in its strange leaves but in the rocks that held it. As he followed rock layers with
Glossopteris
inside, he was able to trace them from
South Africa to
India all the way to
Australia and
South America. To Suess, the
distribution of
Glossopteris
meant one thing: these distinct
continents were once connected to each other in the distant past. In his thinking, the continents were continuous until the seas rose to separate them.

Glossopteris
figured in both discovery and tragedy. In 1912,
Robert Falcon Scott, with four crew members, made a fatal attempt on the
South Pole, only to find, upon arrival, that the Norwegian
Roald Amundsen had beaten him by several months. Photographs reveal the group’s predicament. They were clearly weakened by the long trek, and their faces in the foreground tell of their fatigue and disappointment while standing against
a background of Norwegian tents and flag. Scott’s diary records the difficulties the team experienced pulling heavy sledges on the return trip, how with steadily weakening bodies the weight became too much to bear. Scott,
Henry Bowers, and
Edward Wilson died in their tent in March 1912, and their bodies were recovered when winter broke eight months later. Lying next to their bodies were thirty-five pounds of rock and
fossil. When the samples were brought to the experts at the
British Museum, their significance was revealed. The team had discovered
Glossopteris
at the base of
Beardmore
Glacier, a hundred miles from the South Pole.
Suess didn’t know of this, but it meant that Antarctica too was part of the connections he was envisioning for southern continents.

The deep meaning of boulders, fossils, and the jigsaw pattern of continents emerged from the mind of an iconoclastic German meteorologist.
Alfred
Wegener had two major scientific passions in life: understanding the weather over the ice sheets of Greenland and the geography of Earth. He began his career in
1911 serving as a member of some of the earliest scientific explorations of Greenland, including one venture crossing the entire ice cap on foot. His life ended on the island, where on an expedition in 1930 he died on the ice sheet in an effort to rescue some of his crew who were in need of relief.