Science & Nature Archive

Friday, January 13, 2017

Evolution Book Available Online - From the Beginning

From the BeginningLet's end the week on a positive note. A few years ago, I bought a children's book about human evolution, From the Beginning: The Story of Human Evolution. It was actually a recommendation on a biologist's website, Pharyngula - An updated book list for evolutionists. As PZ Myers put it, it's "An older book that may be hard to get, but worth it for the wall-to-wall drawings of the organisms scattered along the human lineage, from single-celled prokaryote to modern humans." And I have to agree. It may be a little bit outdated by this point, and I did notice a few places where I would have liked to have seen a few things worded a bit differently, but overall, it's a very good overview of human evolution, going all the way back to the very beginning of life. In fact, I'd even recommend it for adults, not just kids.

Well, I got to thinking about that book today, and did a google search on it. And I found something that made me a little excited. The entire book is available online for free from the author's website. So, now I can recommend it to others whole heartedly, knowing that they don't have to hunt it down, but can access it immediately. So, here's the link:


From the Beginning: The Story of Human Evolution (pdf)


If you want to see some of Peters' other books, you can find them here: David Peters Studio - Books.

Well, I guess I'll have one downer in this post, more of a note of caution. As good as that book is, and as talented as Peters is as an artist, he's gotten into a little bit of academic controversy the past few years. He's come up with rather fanciful interpretations of certain fossils, which haven't exactly been accepted by the mainstream scientific community. You can read more about that here, Scientific American blogs - Why the world has to ignore ReptileEvolution.com. Just keep it in mind if you decide to browse Peters' stuff.

Wednesday, November 16, 2016

Book Review - Future Humans

Scott Solomon, a friend of mine who happens to be an evolutionary biologist, has just released his first book, Future Humans: Inside the Science of Our Continuing Evolution. If that name sounds familiar, it's because I mentioned the book a few months ago in the entry, New Book - Future Humans. Now, as I wrote then, I did read and comment on one of the draft manuscripts for Scott, so I may not be the most impartial of reviewers. But I still liked the book very much and would recommend it to anyone with an interest in ongoing human evolution.

I can't sum it up much better than the description from the publisher's site:

In this intriguing book, evolutionary biologist Scott Solomon draws on the explosion of discoveries in recent years to examine the future evolution of our species. Combining knowledge of our past with current trends, Solomon offers convincing evidence that evolutionary forces still affect us today. But how will modernization--including longer lifespans, changing diets, global travel, and widespread use of medicine and contraceptives--affect our evolutionary future?

Solomon presents an entertaining and accessible review of the latest research on human evolution in modern times, drawing on fields from genomics to medicine and the study of our microbiome. Surprising insights, on topics ranging from the rise of online dating and Cesarean sections to the spread of diseases such as HIV and Ebola, suggest that we are entering a new phase in human evolutionary history--one that makes the future less predictable and more interesting than ever before.

The book is well grounded in evidence. In fact, most of it is about actually observed human evolution, both in our very recent past just prior to the industrial revolution, as well as what can be gleaned in modern industrial societies. Of course, that makes the speculation far less sensationalistic than doe-eyed anime characters or web-footed aqua-people, but you probably won't lose any bets going along with Scott's reasonable inferences.

There were many good passages I could quote from the book, but here's one that I especially liked.

At it's core, evolution is about babies. Forget survival of the fittest - the only reason survival is important in evolution is because you cannot reproduce when you're dead. Ultimately, selection favors whatever traits result in making the most babies, grandbabies, and so on.

Scott went on to explain how natural selection has shifted in modern societies. When the vast, vast majority of people survive into adulthood, it becomes changes to fertility that will have the greatest effect on evolution. And that's exactly what many researchers have found - women having children earlier and entering menopause later, increasing their reproductive years and hence their number of offspring. Of course, the researchers have to use statistical methods to try to tease out cultural and environmental influences from genetic ones, but it really does seem as if these are hereditable, genetic changes. And that's just one of the many lessons I learned from the book.

There's a review in New Scientist some might find useful, Future Humans: Just how far can our evolution go?. You can also read an early version of one of the chapters as an article in Nautilus magazine, The Rhythm of the Tide, describing his trip to Ile aux Coudres, an isolated island in Quebec, to discuss what researchers there had discovered of recent evolution in the island's population.

On a personal note, I can say that it's a very different experience reading a draft as a reviewer vs. reading the completed book for pleasure. There's a bit of stress in reviewing the book, intentionally being critical, and trying to find flaws that could be improved. It was much more relaxing reading the book once it was done, and just enjoying it. (I should add that I reviewed it as a member of his target audience, not an expert in the field. I may like to write a bit about evolution on this blog, but I'm no biologist.)

The book was very interesting. It may be a little advanced for an evolutionary naïf, but if you paid attention in your high school biology class and remember the lessons, you'll probably find this book pretty informative. I definitely recommend it.

Friday, November 4, 2016

Understanding Evolution - Origin of Limbs

I recently came across and answered a question on Quora that reveals a misunderstanding I've seen before over evolution. The question was If theory of evolution is true, why aren't there more semi-evolved species with hands coming out of their skulls or other half-baked monstrosities?. It seems to be that some people think that evolution works by creating partially complete versions of what will later be a fully fledged feature of an organism. Obviously, that's not the case. So I figured it might help to explain how a trait like our limbs actually did evolve.

Evolution doesn't have any foresight or planning. Every organism that has ever lived is both the end result of all the evolutionary history leading up to it, and a transitional form to whatever it's future descendants might look like (assuming its lineage doesn't go extinct).

In contrast to what that Quora question implied, evolution doesn't work like this:

Not How Evolution Works
(not how evolution works)

Evolution didn't provide us with a partial arm in anticipation of a fully developed arm down the road. We didn't sprout a bicep, then a forearm, and finally a hand to complete our limbs. Genetics just doesn't work that way. If an organism doesn't have any limbs to begin with, it's not going to create a monstrosity with a partial human limb. Evolution only works incrementally, and every step has to be functional, or else the organism won't survive to reproduce.

So, if our ancient ancestors didn't have limbs, but we do now, how did it happen? What were the types of changes that were small enough to be possible through genetic mutation, but useful enough to benefit those organisms?

First of all, our ancient ancestors looked something like this:

MetaSpriggina Reconstruction & Fossil
(source: New fossil find pinpoints the origin of jaws in vertebrates)

Just to be clear, it's very unlikely that that's actually our direct ancestor. It's probably a cousin of our direct ancestor. So, it's more like our great-great-great aunt/uncle. But, just like you're more similar to your human aunts and uncles than to unrelated strangers, our ancestors were probably pretty similar to that creature. And of course, you can go back and find even simpler ancestors that are more ancient, but I didn't want to go through our entire evolutionary history for this entry.

So, that critter is a very early chordate. It's got some of the same features we do - eyes, a brain, a 'spinal' cord, etc. But it's also missing some of the features we have now - a jaw, bones, and most notably for this discussion, limbs. So, what could those first rudiments of limbs have looked like? Probably something like this:

Hypothetical evolution of paired fins and their skeletal supports
(source: Origin and Comparative Anatomy of the Pectoral Limb: Anthony F. DePalma MD, FACS)

Now, I'm going to be completely honest. That picture is informed speculation based on studying modern animals, genetics, and embryology, since no fossils have been found preserving that type of soft tissue, but it should be clear how skin folds leading to fins would have been a pretty small mutation that would have benefitted our swimming ancestors. From that creature in the top of the image, it's also a small step to then split up those now existing fins into several independent fins - giving those organsims more freedom in how to use those fins.

Once our ancestors had simple fins, then it was a series of small incremental steps to get to more complex fins, like shown in this next picture:

Diagrams illustrating hypothetical evolution of the extremities of diapnoan (I), ganoid (H) and elasmobranch (G) from a fin fold supported by a series of similar radial cartilages.
(source: Origin and Comparative Anatomy of the Pectoral Limb: Anthony F. DePalma MD, FACS)

I like this one because it also shows the branching nature of evolution. It wasn't just primitive fins in a straight line to our direct ancestors. As those populations split up, each newly independent population took its own evolutionary path, each finding different strategies for modifying fins. In one particular lineage (L), it created a fin with fairly robust bones.

Now, that lineage kept on splitting, too. Some populations remained in aquatic habitats, so that today you can still find coelocanths which have fins with robust bones like that. But some of the populations became increasingly specialized for amphibious habitats, and eventually some populations even became specialized for fully terrestrial habitats. Take a look at this next picture:

Tetrapod Limb Development
(source: Berkeley - The origin of tetrapods)

Like the caveat I gave above, most likely none of those organisms are direct ancestors of any of the others, but the oldest ones are similar to the actual direct ancestors (they're all known animals from fossil remains). And you can see how each newer organism and newer limb is only a slight change from the previous one, as well as how each organism has a fully developed limb that serves it quite well.

And remember, as populations split off and each go their own evolutionary way, they can all develop their own independent adaptations and ways of using different features. So, from those early tetrapods, different lineages have modified those limbs in remarkably different directions, but all showing the underlying similarity:

Similarity of Vertebrate Limbs
(source: Pinterest)

It's not just limbs. That's how virtually all features have developed over the course of evolution. You've probably seen octopuses and squids, and know that they have pretty complex eyes, with an iris, cornea, lens, retina, etc. But since we know evolution is true, it must follow that even something as complex as that eye must have evolved through small, incremental changes, with each new change being beneficial. And in fact, we actually do have a pretty good idea how it happened:

Stages of eye complexity in mollusks
(source: Evergreen Comparative Physiology of Vision - Cephalopods)

Note that those intermediate steps are found in existing animals. They're not just hypothetically a type of eye that could exist. They're types of eyes that we know, for sure, exist and are used by different species of animals.

So, just to recap, evolution doesn't have foresight or a plan. For that matter, it's not a conscious entity at all, even if anthropomorphizing sometimes helps to explain it. Evolution only works through small incremental changes, and each of the changes has to be beneficial if the organisms are going to survive and pass those changes on to future generations. Every organism alive, past and present, is in a sense the end result of all the evolutionary history leading up to it. But in another sense, as long as they don't go extinct, evolution never stops, so every organism is also a transitional form to whatever its descendants might be.

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Here are two links with more info on vertebrate limb evolution. I already linked to the first one up above, but I wanted to make sure to call it out as being especially informative.

Wednesday, September 28, 2016

2016 Texas Republican Platform - Part 5, Environment / Climate Change

Republican ElephantThis entry is part of a series taking a look at the latest Texas Republican Party Platform. For a list of all entries in this series, go to the Introduction. Today, I'm going to look at their planks on climate change and environmentalism.

Climate change is arguably the most important issue facing the nation and the world. That's not to say other threats like terrorism aren't also big and deserving of attention, but they don't have the same catastrophic global effects.

Climate change is a threat globally, and a national security threat domestically, with the potential to cause huge amounts of upheaval, disruption, and suffering. And it's not some far off threat. Effects are already being noticed, with more severe weather patterns and natural disasters. Refusing to take action on climate change is both a moral failing and political dereliction of duty.

So, with such a huge issue, you'd expect it to play prominently in any serious political party. You'd expect it to be a major portion of their platform, explaining just how they expect to deal with such a monumental challenge. How do Texas Republicans deal with it? One freakin' paragraph, that doesn't even say how they would address the issue, but calls into question whether it's a real issue at all! Here's the plank, the one and only plank in the whole platform that mentioned climate change:

Protection from Extreme Environmentalists- We oppose environmentalism that obstructs legitimate business interests and private property use, including the regulatory taking of property by governmental agencies. We oppose the abuse of the Endangered Species Act to confiscate and limit the use of personal property and infringement on property owner's livelihood. "Climate Change" is a political agenda promoted to control every aspect of our lives. We support the defunding of "climate justice" initiatives and the abolition of the Environmental Protection Agency and repeal of the Endangered Species Act. [emphasis mine]

That whole thing is bad, but take a look at that part in bold. This is deep into paranoid conspiracy theory territory. Climate change is real, and is a grave threat to society. To dismiss all the evidence in support of climate change and to call it a 'political agenda' is absurd.

The other parts are bad, but hardly surprising. The Republican Party in general just seem to have a problem with environmentalism, or any of the federal agencies that work to help preserve the environment (though of course, they couch it in language of private property and over-regulation).


I guess you could argue that even though the above plank was the only one that mentioned 'climate change', these next two do deal with the topic. But again, they're not encouraging. They're calls to inaction, without any proposal on how to address the issue:

Carbon Dioxide- We oppose all efforts to classify carbon dioxide as a pollutant.
Cap and Trade- We oppose the implementation of any cap and trade (aka "Cap and Tax") system through legislation or regulation.

And as I've written before, the Republican opposition to Cap and Trade is especially irritating because it was a Republican proposal to begin with - a free market method of addressing carbon emissions rather than overly restrictive government regulation.

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Honestly, there are lots of very, very bad sections of this whole platform, but this is the worst. Climate change is the type of existential threat that merits people becoming single issue voters. It's making nations uninhabitable, and could literally change the map. For a political party to actually call the reality of it into question and imply that it's nothing more than 'a political agenda' goes beyond mere irresponsibility. It's reprehensible, and should disqualify the Republican party in the minds of all thinking people.


More info: I've written several times about climate change before. Phil Plait of the Bad Astronomy blog also has quite a bit. Here are links to several entries from Plait, followed by some of the ones I've written.

Climate Change Links on Bad Astronomy:

Climate Change Links on This Site:


Continue to Part 6, Civil Rights

 

Tuesday, September 20, 2016

Is Evolution Falsifiable?

Is the March of Progress InevitableI came across the following Quora question, Is the theory of evolution unfalsifiable?. Although I'm not sure the question was asked in good faith, it's still an interesting question to think about. Here was my response.

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All good science should in principle be falsifiable. The problem is that some fields become so well backed up by evidence, it's hard to conceive how they could be falsified short of ludicrous conspiracy theories or Matrix like scenarios.

For example, take the roughly spherical shape of the Earth. For all intents and purposes, this is a concept that has been proven beyond a shadow of a doubt. You can find multiple Quora threads dealing with flat earth 'theories', such as this one, Let's say I don't believe the world is round. How can one prove the world is round to me?, which lists some of this overwhelming evidence in support of the Earth's true shape. It's really hard to conceive how this concept could be falsified given all that we know. It would take a conspiracy on par with The Truman Show, where everyone we thought we knew was an actor, and we had been misled our entire lives, or an equally ludicrous scenario like the Matrix, where we were living in a simulated reality not at all like the reality outside the simulation. In short, falsifying the roughly spherical shape of the Earth would entail a shake up so huge that we couldn't trust anything we thought we knew about the world.

Evolution in broad stroke approaches that level of certainty. Between biochemistry, biogeography, comparative anatomy, comparative embryology, molecular biology, paleontology, genetics, observed instances, and other lines of evidence, it's really hard to conceive of how the concept could be falsified.

One of the flip answers you'll often hear is rabbits in the Precambrian, supposedly a response from J.B.S. Haldane when asked what evidence he thought would falsify evolutionary theory. But to return temporarily to the flat Earth example, that's like saying that a photograph of a disc world from space would be evidence to falsify round world theory. But honestly, would the image below be enough to convince you that the world was flat? Or would you suspect Photoshop or some other type of hoax?

Flat Earth Illustration

So even if fossil rabbits were claimed to be found in Precambrian deposits, they would be investigated and considered very extensively before being taken as evidence overturning evolution. Could they be hoaxes? Some type of disturbance to the geological column in that locale? A section of Precambrian deposits that were temporarily exposed long enough for some poor ancient rabbit to die and become fossilized there? To be honest, given the vast other data in support of evolution, a single Precambrian fossil rabbit would probably be chalked up to an unexplainable anomaly.

But, supposing more out of place fossils were found than just a single anomaly, or you could find evidence of huge conspiracies among all the world's biologists past and present lying about the evidence for evolution, or you could find evidence for the Matrix and that the real world is far different from this simulation that we're living in, then you might have something in the way of falsifying evolution.

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More Info - I included a link to a Quora thread in the original answer, and I've written about the topic numerous times, myself. So, here are links to that Quora thread and a few of entries I've written.

Image Source 1: Wikipedia, with further editing by me.

Image Source 2: Pinterest - It's actually all over the place without attribution, so I doubt that I've actually found the original. If anyone knows the actual original source, please let me know.

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