In 2021 a team of paleontologists led by Charles Marshall at Berkeley did something clever: they estimated not how many T. rex we have dug up, but how many ever existed.

Their headline answer was about 2.5 billion, spread across the roughly 2.4 million years the species was around, although the uncertainty ranged from 140 million to 42 billion. At any given moment, the central estimate put about 20,000 adults on the continent at once, generation after generation, for longer than modern humans have existed. 

Now set that against how many we have found. The first partial skeleton recognized as T. rex was unearthed by Barnum Brown in Montana in 1902, and it became the name-bearing specimen when Henry Fairfield Osborn formally named the species in 1905.

By 2021, fewer than a hundred T. rex individuals had been found, many represented by a single fossilized bone. Only about 32 were relatively well-preserved post-juveniles held in public museums.

On Marshall’s estimate, that works out at roughly one recovered specimen for every 80 million post-juvenile animals that lived and died. Much of our physical knowledge of the animal rests on that extraordinarily narrow sample.

The math of what is missing

That fossil recovery rate that falls out is comically small.

However, for a T. rex to become a fossil you could visit, it had to die in the right place, get buried fast enough to escape scavengers and rot, survive tens of millions of years of erosion and geological change, and then happen to surface in a spot where a human being was looking. Almost nothing clears all of those hurdles.

The famous individuals bring this home. The great specimens have names, because there are few enough of them to name: Sue in Chicago, Stan, a short list of others that get written about again and again. When a single skeleton can anchor decades of research and a museum’s entire dinosaur hall, you are not looking at a well-stocked archive. You are looking at the handful of tickets that happened to win a very long lottery.

What we build on almost nothing

T. rex is not the poorly documented case. It is one of the better understood dinosaurs we have, a giant, sturdy-boned predator from rock we know how to read, hunted for over a century by people who badly wanted to find it.

If this is what good coverage looks like, roughly one relatively well-preserved post-juvenile in 80 million, then for most creatures that ever lived the record is not thin. It is blank. Whole species, whole families, came and went and left nothing a person will ever hold.

We are not usually reminded of that when we stand in front of the mounted skeleton. The display is confident. The posture, the coloring in the illustration beside it, the running speed on the little plaque, all of it reads as settled fact. A great deal of it is careful, honest extrapolation from a few bones and a lot of comparison with living animals, which is real science and often turns out right. But the certainty of the presentation and the scarcity of the evidence sit in an odd relationship, and I think it is worth holding both in mind at once.

None of this is a knock on paleontology. If anything it is the opposite. The impressive thing is not that our picture of T. rex has gaps. It is that anyone can say something reliable at all, starting from such a tiny fraction of the animals that lived and reasoning outward with that much care.

The wonder is not that we know so little. It is how much we have managed to reconstruct from so nearly nothing.

The post A 2021 estimate suggested that about 2.5 billion Tyrannosaurus rex lived, while only 32 relatively well-preserved post-juvenile specimens were then held in public museums — roughly one for every 80 million animals. And T. rex is one of the better represented large theropods appeared first on Space Daily.

Picture the den in early summer. Some of the adult wolves have left to hunt, which can mean being gone for the better part of a day or longer and covering ground a person would struggle to walk.

The new pups are too small to follow and too helpless to leave truly alone. So they are not left alone. A pack member often stays behind, and that wolf may be an older brother or sister from a previous litter, on babysitting duty.

Wolves are one of a fairly small number of animals where the raising of the young is a group effort rather than a job for two. Biologists call it alloparenting, care given by animals other than the mother and father. In a wolf family it often falls to yearlings and other nonbreeding wolves that have not yet left to start families of their own. The Wolf Conservation Center describes them babysitting the pups, regurgitating food for them and playing with them. 

The most striking part, to me, is the food. A yearling that has fed at a kill will travel back to the den and regurgitate meat for the pups, delivering a meal it carried home inside itself. It is not glamorous. It is also a genuinely generous act by an animal that could simply have eaten and kept walking. The parents do it too, but research on wild wolves found that all adult pack members, including yearlings, regurgitated food, so the pups can be fed from several directions at once.

There is a quiet division of labor worth noticing. In one Idaho study, nonbreeding females attended dens and rendezvous sites about twice as often as nonbreeding males, suggesting that older sisters may take a closer hand in caring for the new pups.

The younger wolves may also be gaining practical experience. By the time a yearling leaves to raise its own litter, it may already have spent a season or two feeding, guarding, and minding pups. It has, in the most practical way, learned the job before it needs it.

All of this can have a hard payoff. Spreading the care across the pack means the pups can be watched, fed, and defended while other wolves hunt, part of what makes a pack so resilient. In a long-term study of reintroduced red wolves, helpers were associated with higher pup mass and survival at low population density, although the survival benefit disappeared at high density. Gray-wolf research likewise shows that the relationship between pack size and surviving pups varies with ecological conditions. Extra hands are not automatically better in every place and every year, but they let a wolf family divide the essential work of guarding and provisioning.

What I like about it is how unfamiliar it makes a familiar animal look. We are used to thinking of wolves through the language of dominance and the lone hunter. The reality on the ground, in early summer, is a young pack member staying home to mind the babies while others hunt, and then bringing dinner back for everyone.

It is closer to the cooperative way humans have raised children across much of our history, with older children and other relatives helping to care for and provision the young.

The pups will grow, and in a year or two some of the babysitters will leave to become parents themselves, carrying the whole routine somewhere new. It is a small, well-run system, repeated from one generation to the next

The post In a wolf pack, older brothers and sisters often help with the babysitting. While some adults are away hunting, wolves from previous litters guard the new pups and carry food back for them — an all-hands approach to raising the young that can improve a pup’s chances of surviving appeared first on Space Daily.

There is something difficult to grasp about the number of lakes in Canada. A few thousand would already seem excessive. Tens of thousands would be hard to picture. Canada has more than two million by federal estimates, scattered across a landscape shaped by ice.

The number is so large that it almost stops meaning anything. You could visit a different Canadian lake every day for an entire lifetime and still see only a small fraction of them. On a map they appear as blue flecks, crowded together across the north, but each one is a real body of water with its own shoreline, islands, depths and surrounding ecosystem.

What does “60 per cent of the world’s lakes” mean?

The often repeated claim that Canada holds around 60 per cent of the world’s lakes needs some qualification. There is no universally agreed count of every lake on Earth, because the result depends on what size of body is included and how lakes are distinguished from ponds, reservoirs and seasonal water.

One of the most widely used global databases, HydroLAKES, maps about 1.4 million lakes and reservoirs with a surface area of at least ten hectares. According to research describing the database, roughly 62 per cent of those water bodies are in Canada.

That does not mean Canada contains 62 per cent of the world’s freshwater. It means that nearly two-thirds of the lakes included in that particular global dataset lie inside Canada. The country nevertheless holds an enormous amount of water, and fresh water covers about eight per cent of its surface area.

What the ice left behind

The explanation lies largely in the Ice Ages. During repeated periods of glaciation, much of Canada was covered by continental ice sheets several kilometres thick. These were not static blocks of ice. They moved slowly across the land, grinding against the bedrock beneath them.

As the glaciers advanced and retreated, they scraped away soil and rock, deepened existing valleys and gouged countless depressions into the surface. When the climate warmed and the ice melted, water collected in those hollows.

The glaciers also carried enormous quantities of stone, sand and clay. As they withdrew, they left behind ridges and irregular piles of debris that blocked rivers and trapped meltwater. Some lakes formed in basins carved directly into rock. Others developed behind natural dams of glacial sediment.

This process happened across an immense area. The Canadian Shield, which stretches around Hudson Bay and across much of central and eastern Canada, is particularly full of exposed rock, shallow soil and water-filled depressions. From the air, much of the region looks less like solid land dotted with lakes than a broken mixture of rock, forest and water.

A landscape made of water

Some Canadian lakes are among the largest in the world. The Great Bear Lake and Great Slave Lake dominate the Northwest Territories, while parts of four of the five Great Lakes lie within Canada. But the extraordinary total comes mainly from the vast number of smaller lakes scattered across the country.

Many are remote enough to have no roads, settlements or permanent names. Some can be reached only by aircraft, canoe or long journeys through forest and tundra. Others sit within sight of towns and cities, forming part of ordinary Canadian life through fishing, swimming, transport, tourism and hydroelectric power.

The abundance of lakes also creates problems. Water may appear limitless, but it is unevenly distributed, often far from the country’s largest population centres. Pollution, warming temperatures, invasive species and changing rainfall patterns can still damage individual lakes, no matter how much water exists elsewhere.

Closing thoughts

Standing beside one cold lake in the Canadian bush, there would be no way to sense that it was one of more than two million. That is the odd thing about scale. From the shore, the lake is simply a place: water against rock, trees reflected on the surface, perhaps an island in the distance. Only from the level of a map or a database does it become part of something almost impossible to imagine. 

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In the middle of the nineteenth century, a Dutch army recruit stood on average around five feet five inches. That was short even for the time, shorter than many of his European and American contemporaries, and nobody looking at the Netherlands then would have picked it as the future home of some of the tallest people on Earth. Yet that is exactly what happened. Young Dutch men born in the Netherlands now measure nearly 1.84 metres on average, almost exactly six feet, and the country consistently ranks among the world’s tallest. In the space of about 150 years, one of the shortest populations became one of the tallest.

Twenty centimetres in a century and a half

The scale of the change is easy to say and hard to feel. Dutch men gained roughly 20 centimetres, close to eight inches, between the mid-nineteenth century and the modern era. That is not the kind of drift you expect from a stable population. It is a population visibly rebuilding itself, generation by generation, each cohort of children arriving taller than their parents for decade after decade until the whole nation had grown into a different shape.

Height works this way because it is only partly written in your genes. Your genes strongly influence the range of height you might reach. Where you fall within that range depends heavily on the years between birth and adulthood: whether you got enough good food, whether illness kept interrupting your growth, and whether the conditions around you let a body spend energy on getting tall rather than just getting through. A child who is well fed and rarely sick is more likely to grow toward the top of that range. A child who is not, may not. Multiply that across millions of children and stature becomes a kind of national report card.

Milk, money and doctors, not evolution

So what changed in the Netherlands? The answer is less dramatic than the transformation, and I think that is part of what makes it interesting.

The country got richer, and it got healthier. As researchers behind a Dutch Growth Study concluded, “Main contributors to the increase in height may be improved nutrition, child health, and hygiene, and a reduction of family size.” Prosperity, diet, healthcare and hygiene pulled in the same direction for generations, and the population climbed.

There was, for a while, a more exciting theory. In 2015 a study in a Royal Society journal suggested the Dutch might also be evolving taller, because taller Dutch men appeared to be having slightly more children, which could nudge the genes associated with height upward over time. It is a genuinely appealing idea, natural selection caught in the act in a modern European country. But it is worth being careful here, because the same lead researcher later put numbers on it. A 2023 simulation estimated that natural selection could account for only 0.07 to 0.36 centimetres of the change between 1850 and 2000. Against a gain of nearly 20 centimetres, that is a rounding error. The dramatic explanation turns out to be a footnote, and the dull one, better food and better health, did nearly all the work.

What a body remembers

I keep coming back to the idea that a population’s height is a physical record of its recent past. You cannot easily fake it or rush it, and it does not respond to a single good year. It responds to conditions sustained across a childhood, and then across many childhoods in a row.

When a country gets taller the way the Netherlands did, the bodies of its people are, in a real sense, remembering decades of enough food and decent medicine. The change is written into skeletons before it shows up in any history book.

It cuts the other way too. When researchers see average height stall or fall in a population, it can point to something going wrong in childhood: nutrition slipping, healthcare thinning out, or hard years landing on the young. 

The Dutch story is often told as a curiosity, a fun fact about a nation of unusually tall people ducking under doorframes. I think it is better read as evidence of something quietly hopeful. Give children enough to eat and keep them healthy, reliably, for long enough, and you can watch the result stand up in a crowd a century later. The Netherlands did not stumble into being tall. It fed and cared for a very long line of children, and the height is what that looks like from the outside.

The post In the mid-nineteenth century, the Dutch were among the shortest people in Europe. Today they remain among the tallest on the planet, with young men standing about 1.83 metres on average. Rising prosperity, better nutrition and improved healthcare added nearly 20 centimetres in roughly 150 years appeared first on Space Daily.