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When offspring carry new combinations of genes that can take advantage of resources in the environment faster than other organisms in their ecosystem, they are bound to succeed.
And one’s chief competitors are seldom other troublesome large animals: Humans really have very little trouble keeping up with and living around lions and tigers and bears. Instead, our most troublesome bad guys are germs and parasites. These are what can kill us or disable us to the point where we cannot produce or care for offspring.
The key to fighting germs and parasites seems to be sex.
In evolution, we have to run constantly; we have to continually come up with new combinations of genes to keep our genes in the game.
Human farmers and breeders make the decisions as to which genes get selected to pass on to the next generation. Darwin thought of this as gene selection induced artificially (though he did not use the terminology of genetics,
How can you take the lack of evidence of a plan as evidence of a plan? That makes no sense.
The oldest known fossils are of bacteria that apparently lived in ponds or a shallow sea located in what is now western Australia.
They are fossil mats of bacteria, called stromatolites, whose metabolism led them to excrete calcium carbonate, chalk, the stuff of
seashells and limestone. The ancient ponds dried up for some climatological reason, and these bacterial mats turned to st...
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The farther back in time we carry out an accounting of the number of different living things on Earth, the fewer different kinds we find.
The implication is that evolution naturally leads to an increasing number of different kinds of living things.
In this way, it is much like a tree. The higher a tree grows, the more branches will grow and bifurcate; each bifurcation leads to an...
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scientists realized that animals and plants have much more in common with each other than they (or we) have with almost all of the other living things here on Earth.
As I write, we now consider nature to have given rise to three or four foundational types of living things, or domains of life. I’m going with four. We have Bacteria, Archaea (microbes that are fundamentally different from bacteria), Eukarya (that’s us, animals and plants together),
we should continue to go with the old, increasingly fine designations. If we did, it would go domain, kingdom, phylum, class, order, family, genus, and species.
That’s why we are said to be Eukaryotes; it’s from Greek words meaning “having nut” (having nucleus). The Archaea and Bacteria are Prokaryotes, meaning “before nut” (before nucleus).
Biodiversity can be quantified. It is a measure of the results of evolution. It is like a master index of all the populations of all the species that have come into existence today and all those that have been lost to extinction.
When we look at the fossil record, we see that biodiversity has been generally on the rise since the beginning of life some 3.5 billion years ago: The Tree of Life keeps getting bushier. If indeed we all are descendants of a common ancestor, this is just what we would expect. With every reproduction, there is a chance for a mutation that may or may not prove to be beneficial to the offspring. If it’s beneficial, that organism, along with its genes, survives well enough to reproduce, passing its genes forward one more generation. With this happening over and over and over, all day, all the
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Replication after replication, with chance after chance of small changes, leads to a gradual spread of good-enough traits that help a species compete. The opening of relatively unpopulated environments and the isolation of small populations encourage the emergence of new species. With more different kinds of living things coming into existence, more and different environments and energy resources could be exploited.
science education we like to say that energy is what makes things go, run, or happen. So it is with living systems. They (we) need energy to live, to move, to grow, and reproduce. If we ask ourselves, “Where is there the most energy available to living things?” we come up with two sources at least. The first is sunlight. The second is the primordial energy of Earth’s interior. The same is probably true of life on other worlds (if it exists), as I’ll discuss later.
The areas of Earth with the most energy input are also the areas with the most biodiversity.
In contrast, solar energy falls on every part of the planet’s surface, with an intensity of up to 1,000 watts per square meter.
They reproduce more quickly and we end up with more diversity. Deep in the cold ocean, life thrives only where there’s enough energy to feed the system.
Again, the greater amount of sunlight(source of energy), the more biodiversity in an ecosystem. How does this validate evoulution?
More diversity makes for a more robust ecosystem.
Diversity begets more diversity.
On modern large-scale farms, we see thousands of hectares or acres of a single crop. While this “monoculture” makes it easier for farmers and farm machinery to harvest the crop when it’s ripe or ready, it also makes the crop more susceptible to attack by a single pest or parasite.
Diversity leads to resilience.
The point is this: Diversty in the ecosystem provides resilience to species when changes occur
It is estimated that humans are driving species to extinction at least a thousand times faster than the otherwise natural rate.
We cannot know what will go wrong or right. However, we can be absolutely certain that by reducing or destroying biodiversity, our world will be less able to adapt. Our farms will be less productive, our water less clean, and our landscape more barren. We will have fewer genetic resources to draw on for medicines, for industrial processes, for future crops.
The fossil record isn’t a tidy clean recording.
Most living things never get fossilized, and most fossils end up in places where they are impossible to discover.
The resting place generally has to be wet in order for the organism to get buried effectively. Then that wet sand or soil has to dry out completely so that microorganisms don’t rot the remains. Then it has to sit there for years and years and years, generally millions of years, while minerals slowly trickle through and turn once-living structures to stone.
Fossilas need to be buried(preferbly live) under wet grave, dry out,and then receive minerals in order for the body tobturn into stone.
The deeper we dig, the older the animals and plants we find.
shale, the sedimentary rock that old-style classroom blackboards were made of.
Along with that, is it that life on Earth actually increased in diversity by a factor of twenty, or is it that the fossil record doesn’t reveal much about the past until living things came up with hard shells that were readily preserved in solid rock as fossils? The Cambrian Explosion is more (or was more)
In general, the difficulty of making fossils guarantees that the fossil record will be full of gaps (or maybe “skips,” for those of us youthful deejays or old fogies familiar with vinyl records).
The Earth is 4.54 billion years old. Its crust has repeatedly broken up, moved around, melted, and reformed.
One of the great challenges in reconstructing a mass extinction is making sense of what happened when. In the same way we have divided living things into a hierarchy of divisions—domain, kingdom, phylum, class, order, family, genus, and species—geologists have broken apart the long history of our planet into eon, era, period, epoch, and age.
All of those years are currently considered to be part of just one single geologic eon, which goes by the wonderful name: the Phanerozoic Eon (Greek for the visible eon, the one we can see). The Phanerozoic is in turn divided into three geologic eras: Paleozoic, Mesozoic, and Cenozoic.
Looking at Earth from space, as we can nowadays with our sophisticated satellites, we can observe climate as it is changing today.
The first potential extinction triggers are volcanoes. If you ever get a chance, I strongly encourage you to visit Mount St. Helens National Volcanic Monument in Washington State in the U.S., where entire ecosystems vanished when the mountain blew its top on May 18, 1980.
Regardless of where they strike, large asteroids would boil seas, fill the air with dust and acidic compounds, and perhaps induce carbon dioxide to cook off out of the rocks and into the air, triggering a strong greenhouse effect, all of which in turn would change the world’s climate faster than living things could adjust to.
Industrial emissions are one way humans are changing this planet, but not the only way. We are also directly killing countless species at a rate that dwarfs the rates estimated in the previous Big Five extinctions. We are killing them mostly by destroying their habitats. We are forcing countless species to move, driving them from their ecological niches. The extra carbon in the air is holding in the Sun’s heat; it’s also soaking into the ocean, forming carbonic acid (like in soft drinks), which is compounding our looming troubles.
The problem is not just that the ecosystems are changing; as many people note, conditions on Earth have been changing for as long as the planet has existed. The problem is the rate at which we are causing the changes. It’s the speed that has us headed for the sixth mass extinction.
Let’s take a closer look at that asteroid that struck at the end of the Cretaceous. A 10-kilometer-wide rock might not seem all that bad, considering it was going up against our 13,000-kilometer-wide planet. But the asteroid was probably moving about 20 kilometers per second, or around 45,000 miles per hour. At such speeds, it carried the energy of a thousand billion (a trillion) tons of TNT.
Natura non-facit saltum—nature does not make leaps—was the common wisdom at the time, and the belief in the steady unfolding of geologic history was called uniformitarianism. To his credit Lyell realized how much time he was dealing with.
Darwin called the missing fossils, “… the most obvious and gravest objection which can be urged against my theory…”
Indeed, many will point to the fact that there are major omissions in the fossil record that would seem to undermine the theory of evolution .
Punctuated equilibrium explains why we are missing a great many transitional forms in the collections of fossils kept in institutions around the world.
The effect of punctuated equilibrium jumps right out. It’s the reason we just don’t see many of the transitional fossils. There are inherently fewer of them, and the changes happen quickly.
Described this way, a gene is a construction plan that ultimately determines the order of amino acids needed to create a specific protein.
