Ocean planet: Cousteau, whales with legs, and aquatic humans
Our blue planet, as far as we know, is unique in the universe. There is a need to revalue water and the seas, in times of drought, pollution, overexploitation and overfishing. That thought came to me when I recently had the privilege to look in the eyes of two beautiful white beluga whales at the Oceanogràfic aquarium in Valencia. As oceanographer Jacques Cousteau once said, "People protect what they love". In this article I muse on some peculiarities of the sea and its plethora of inhabitants. Guess which 'cousins' of cows found their way back from the land to the sea millions of years ago. And once upon a time, humanity too stood at the edge of the water.
Author: Kathelijne Bonne.
On 4 March this year, cheers erupted from the UN New York offices: It was finally agreed that 30 per cent of the world's ocean must be protected by 2030, for the health of the ocean is directly related to the health of the planet, humanity and society. Marine ecosystems, which are catastrophically collapsing according to the latest IPCC reports, could recover spectacularly if well-chosen regions are left undisturbed.
This was called for already 30 years ago and probably earlier, e.g., by documentary filmmaker Jacques Cousteau, pioneer of underwater filming and one of the first true activists. In 1992 he attended a pivotal UN environment conference in Rio de Janeiro, during which he urged world leaders to protect the oceans. Although they were eager to be photographed with Cousteau, they would not have much to say to him today regarding their promises at the time. The compromise of protecting 30 per cent of the oceans therefore comes late, but better late than never. Many existing Protected Marine Areas (MPAs) have already proved that not only marine biodiversity but also the traditional fishing of coastal communities can be boosted.
It may be time to revitalize our personal relationship with the sea.
Why does the sea attract people?
Water is the source of all life. It exerts an incomprehensible attraction on us. A shimmering water surface, babbling brook, breaking waves, we all get into a positive, meditative stream of thought when seeing and hearing it. It stretches our consciousness open, from daily concerns to the larger questions and mysteries of life, from the here and now to the distant past and future and to the beauty and vastness of the planet. Marine biologist Wallace Nichols wrote a book about our 'Blue Mind'; how the sea heals us and makes us happy. I wonder if our aquatic past could explain our curious fondness for the sea? We'll come back to it further on.
Microcosm to Macrocosm
Water is has no shape; it moves incessantly and intangibly. Yet repetitive patterns can be recognized in the rippling surface of water, and when it freezes, water becomes extremely geometric. No two ice crystals are identical. More than a century ago, American Wilson Bentley photographed snow crystals under the microscope and made an unparalleled collection of snow micrographs. I discovered his pictures, and all sorts of other natural patterns, in the book The Cosmic Dance: Finding Patterns and Pathways in a Chaotic Universe by Stephen Elcock.
When in liquid state however, water provides its best qualities, the description is less poetic though: Chemically, water is a polar medium, that is, water molecules have a positively and negatively charged side (they are 'polarised'), and readily pull other substances apart so that the individual components are dissolved in the water and can undergo other reactions. Microscopic life in the sea combines calcium and carbon dioxide into chalk to form skeletons, which they use to make shells and coral reefs. On the other hand, water is not strong enough to pull apart life itself, DNA strands and cells. This is precisely why water is the ideal medium for life.
Lately, space agencies are obsessed with exoplanets. They are specifically searching for planets on which water can exist in a liquid state so that life is possible. Several potentially habitable planets have already been idetified, such as in the Trappist solar system, which has no fewer than seven Earth-like exoplanets. However, it is not yet certain whether there is a life-giving blue planet like ours among them.
Fish get legs
Earth's oceans formed not long after the big impact that formed the moon. Earth cooled and water vapour rained down from the dense atmosphere until the world became a ocean planet. Life emerged not long after, about 4 billion years ago. It was only during the Silurian period (443 to 419 million years ago) that the first organisms ventured above the sea surface. The best-liked example is a fish that starts scurrying around the shores, venturing into the muddy environment just outside the water. Its fins become legs and eventually it becomes a land animal. Although this example is the preferred metaphor of our transition from water to land, these fish-like creatures were probably preceded by algae, fungi, plants, and arthropods such as centipedes, arachnids and insects (the fish on the land needed to eat too).
Why took life so long to leave the sea? The oceans are so immensely vast that it may not have been necessary in the early days. There was room for everyone, and in the Precambrian, competition between organisms was not as fierce as it has been since the beginning of the Cambrian; the time of the great explosion of life and when animals first developed protective exoskeletons. It is more likely however that the ozone layer, which blocks harmful ultraviolet radiation, grew denser, allowing life to survive in ever shallower water, and eventually on the land.
Whales in the Sahara
More than once in prehistory, animals, as well as plants, returned from the land to the water. Most spectacular in their return to the sea were the cetaceans, the largest animals on Earth. In the Eocene, the ancestors of whales and dolphins split from the ancestors of the even-toed ungulates (Artiodactyla), from which cows, goats, deer, pigs, camels, gazelles, etc. also descend. Of all even-toed ungulates, whales are most closely related to hippos.
Wadi Al-Hitan in Egypt, the Valley of the Whales, boasts a large collection of fossil whales. These wonderful beasts belong to the suborder of the Archaeoceti: ancient whales. They lived in the Eocene and early Oligocene (45 to 30 million years ago), when much of North Africa and the Sahara was submerged by the now vanished Tethys Sea. The ancient whales of Wadi Al-Hitan epically illustrate the transition from terrestrial to marine animals. It took eight million years to evolve from a terrestrial quadruped to a streamlined marine mammal. The earliest whale ancestors still had four legs, which became flippers and then fins, which probably during intermediate stages still allowed them, like seals, to hop around on land close to shore.
But more and more they withdrew to the sea; they had found a new niche. They lost their fur, the hind legs disappeared, and developed subcutaneous fat (blubber), enabling them to swim faster and insulate themselves better from cold.
Primal whales of the Eocene: (1) Skeleton of Durudon atrox from Egypt (Ellen/Wikipedia), (2) Ambulocetus and (3) Maiacetus from Pakistan, (4) Dorudon from Egypt (2, 3 and 4: Nobu Tamuro/Wikipedia).
Belugas back to sea
Today there still are whales on land, but they didn't choose to. At the Oceanogràfic aquarium in Valencia I met two belugas, a special kind of toothed whale: white Yulka (a female) and white-gray Kylu (her son). Kairo, the father, passed away not long ago in Valencia, his heartbreaking decline and lethargy during his final weeks caused great concern among visitors to the center. Several animal rights organizations are working to urge aquariums worldwide to repatriate all whales and dolphins to the sea, which has been done for the now famous belugas Little White and Little Grey, who were flown by plane from Shanghai to a marine sanctuary in Iceland. Jane Goodall and her ethics committee, including Dr Koen Margodt from Belgium, have made an appeal to end the keeping of cetaceans in captivity.
And what about our own species? Where is our place between land and sea?
Nowadays, people live all over the world, but they prefer to live by the sea. Almost everybody enjoys wading in the shallow water along the seashore, and apparently, we have been doing that for longer than we can remember. According to the Waterside Hypothesis, humans acquired their specific characteristics (bipedalism, walking upright, etc.) by adapting to a life in and near water.
This hypothesis easily explains our attraction to water. According to the most modern views of the Waterside Hypothesis, developed among others by fellow Belgian Dr. Marc Verhaegen, our ancestors, including Homo erectus, would have migrated via the coasts to remote islands in Southeast Asia. Early man waded, swam and dove, looking for crustaceans, an easy and rich food source containing unsaturated omega-3 fat, thanks to which our brains grew larger.
Unlike land mammals, we have a lot of subcutaneous fat. Could that be blubber like in marine mammals? Did we lose our fur as an adaptation to an aquatic life? Going deeper in the past, our more distant ancestors and relatives, several species of great apes, waded and climbed in watery swamp forests, which very early on contributed to the upright (orthograde) posture of the spine still seen in many apes.
Intermediate stage between land and sea animal?
Is it possible that like the ancestors of whales and pinnipeds, these water-adapted early humans (unconsciously) undertook a return to the sea, and were a kind of intermediate stage between land- and sea animal?
At some point however, humans took a U-turn towards living on the mainland. Evolution is gradual and aimless, and can, at any time, due to changing circumstances, turn in another direction. Indeed, one is never really "evolving towards," but rather one is trying to "adapt as best as possible to," and characteristics that are advantageous in certain circumstances will be favored by evolution. Humans became increasingly clever (maybe due to the fatty acids in shellfish?) and began to use tools and weapons, and to master fire, which gave them immense advantages that greatly helped them to populate the diverse habitats of the planet.
But no matter how intelligent we have become, water remains a commodity of which we need a great deal (a 'western' person about 7 cubic meters per day), yet which we do not control as well as we would like. Massive amounts of water are needed to produce food, especially meat, and in various industries (think clothing). As we have transformed our own habitat - there is less and less nature - the patterns of water supply are also becoming more erratic. Amidst floods and droughts, the balance got lost.
A renewed attention and appreciation for water is thus an urgent necessity. For, as wisely noted by Jacques Cousteau, the more we appreciate it and find it beautiful, the more we will do our best to protect it. Only then we'll be able to continue to dream of amazing things and free of worries as we peer out to sea.
Sources: see links in the text.
You can deepen your knowledge on oceans through reading about the Tethys Sea, the vanished realm that now lies in the mountains, as noticed by Swiss Eduard Suess in the nineteenth century when the foundations of the idea of a turbulent planetary past with moving continents, i.e., plate tectonics were laid. The Tethys' last vestige is the Mediterranean Sea, which dried up almost completely during the Messinian Crisis. Water is what space scientists are looking for on exoplanets, of which some may be habitable if there is water. The Waterside Hypothesis of human evolution posits that our ancestors adapted to a life near the water and along coasts, at some point in prehistory.
Article written by Kathelijne Bonne, geologist and soil scientist.
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