Great Company, Great Conversation

I just spent a great evening with other Darwin Day participants. There were about 10 of us, and we had a scintillating conversation about life, the universe and everything.

Special thanks to Stefan for organizing the event. I would also like to thank Ralph, Chinmaya, Xianghong, Clara, Weixian and others (sorry I forgot some of your names, please leave a comment to remind me!) for the interesting discussion and insights.

Cheers!

Happy Birthday Mr. Darwin!

Today is the 200th anniversary of Charles Darwin's birth.

On this occasion I would like to write a short essay to reflect upon his academic achievement and its wider impact on humanity:

1. Darwin was the first scientist to propose a viable mechanism for biological evolution - natural selection.

His crucial insight stems from two basic observations:

First, that organisms tend to have more offspring than the environment can support.

And second, that every offspring differs slightly from its parents and has the potential to pass down these different traits to the next generation.

Thus, the higher reproductive success of individuals who are able to survive in that particular environment causes the population to evolve adaptive features, in small incremental steps, that are suited to that environment.

Should a population be split into reproductively isolated subpopulations (due to geographical separation, for example), driven by excess reproductive fecundity and differential survival each subpopulation will gradually adapt to their new environments and eventually become so different from each other that they can no longer interbreed.

This explains the origin of species diversity.

2. While Darwin's discovery of natural selection is important, it is the direct implication of biological evolution - that all living organisms are fundamentally related - which has attained a greater impact on biology and wider society.



















Other mechanisms of evolution may have been discovered since then, including mutationism by Thomas Morgan and genetic drift by Motoo Kimura.

But even today, 150 years after the first publication of his On the Origin of Species, Darwin's central idea has withstood the test of time.

Palaeontology, comparative anatomy, biogeography, population genetics, biochemistry and more recently, molecular genetics have all validated the basic truth of Darwin's assertion - that all life on Earth shared one (or a few) common ancestors in the distant past, and that we are all cousin species in an immense Tree of Life.

Common descent is a powerful concept not only because it unifies all of biology as an academic subject, but also because it results in a strikingly different worldview from the anthropocentric views created by old cultural traditions.

With the acceptance of common descent comes the understanding of the interconnected relationships between living organisms, the realization of both the resilience and fragility of life, and the appreciation of the need to have sustainable strategies to allow human civilization to coexist harmoniously with other constituents of Nature.

This worldview underpins a myriad of diverse fields such as biodiversity, conservation biology, infectious disease biology, drug discovery, biotechnology, renewable energy technology and the environmental sciences.

3. The achievement of Darwin stand at least as an equal to that of Isaac Newton or Albert Einstein, not because of any technical ingenuity or mathematical precision, but because of its well articulated ideas supported by meticulous attention to details, its wide ranging impact and the fact that it was published in direct opposition to the cultural climate of its time.

Darwin's life work exemplifies the spirit of scientific inquiry - that a discovery, no matter how bizarre or counterintuitive or socially unacceptable, must be clearly expressed, thoroughly investigated and courageously defended.

BBC: Tree Of Life

Here's a nice animation of common descent, which is part of the "Charles Darwin and the Tree of Life" programme narrated by Sir David Attenborough.



I hope that the full documentary will be shown in Singapore someday.

Pipette tip to The Biology Refugia.


Would you like to know more?
- Nature Video: David Attenborough on Darwin (YouTube)

PBS Documentary: Evolution

I won't be writing a detailed overview of Darwin's personal life and academic contributions, since I'm quite sure that there are already many good books and blog articles about this subject matter.

Instead I will highlight this excellent documentary produced by PBS in 2001. If you haven't seen it before and have a couple of hours to spare, do check it out.



Click the following links to continue:

Part 2
Part 3
Part 4
Part 5
Part 6
Part 7
Part 8
Part 9
Part 10
Part 11*

What I like about this documentary is that they consistently emphasize that evolution happens to populations, not to individuals. It also touches upon the DNA evidence of common descent (with a brief primer on comparative genomics), which is important to demonstrate to the viewers that evolutionary biology is not only a "historical science" of fossilized remains.

A minor quibble with the documentary is that they did not mention the fact that natural selection also predicts that a population in a static environment should not evolve (due to purifying selection), but today we know this is not the case, certainly not at the molecular level.

Thus, the appearance of enabling mutations by neutral drift could be an important causative factor to evolutionary change, relegating natural selection to the secondary role of preserving changes. The issue of whether natural selection or mutation plays a more significant creative role in the appearance of evolutionary novelties is a genuine scientific debate that continues on today.

I can understand why they left it out though - this nuance is unlikely to interest people outside the field, and irrelevant to the evolution-creation culture war, since there are no current scientific mechanisms of evolution, Darwinian or not, that dispute common descent.


Would you like to know more?
- Controversy in Evolution (old Fresh Brainz video)

*PS. Notice the "Petunia" insider reference?

Darwin Day In Singapore

It seems that there are no official Darwin Day activities in the Science Centre or the universities in Singapore, but there is an event organized by the Singapore Futurists Society which is open to the public.

Check out their event website on Facebook: Singapore Darwin Day 2009 - the BIG 200!!

If you're not on Facebook, here are the details of the event:

Date: 12 February 2009
Time: 19:30 - 21:00
Location: Geylang East Ang Mo Kio Community Library*
Street: 4300 Ang Mo Kio Ave 6
Email: Stefan.Pernar@gmail.com

I'll try my best to make it for the event. See you there!

*Update 11 Feb 2009: Change of venue to Ang Mo Kio Community Library

Beauty Of The Journey

There are only a handful of books that had a memorable effect on my life.

One of them is a Scientific American book on psychology I read in junior college that I mentioned in an earlier post.

Another one is a book on the Pioneer 10/11 space mission that I read during secondary school (which introduced me to the terms "principal investigator", "photopolarimeter and "RS232").

Earlier still is a big picture book on human evolution that I read when I was in primary school. I recall picking it out from the adult section of the Bukit Merah library - I was never content with children's books and often sneaked "upstairs" to where the good stuff was.

It was a big, heavy book with many photos of the original hominid fossils.

By today's standards, the relationship shown in the book is simplistic and too linear (something like Proconsul -> Ramapithecus -> Australopithecus -> Homo habilis -> Homo erectus -> Homo sapiens).

Maybe most of these remains once belonged to simple individuals just trying to eke out a living in a harsh environment. Not all of them are virtuosos who can produce amazing cave art or preside over elaborate funeral rituals.

But without them, we wouldn't be here.

Did they ever look up at the skies in wonder? Could they have ever imagined that their descendants would one day spread out throughout the globe and walk on the Moon?

Looking at the photos of our ancestors gave me a solemn, almost sacred feeling and instilled in me a sense of respect for the past struggles of our forebears.

To appreciate the magnitude of the explanatory and unifying power of the field of knowledge founded by Darwin and Wallace that many years ago, here are some posters that illustrate various aspects of biological evolution.

I'll let the pictures do the talking.


















Evolution of plants



















Evolution of animals
















Evolution of the amphibian skull


















Evolution of the bird wing



















Evolution of the mammalian jaw



















Evolution of the whale










Evolution of the human skull


Would you like to know more?
- Transitional Vertebrate Fossils FAQ (TalkOrigins)

Give Us A Hand

Some of my readers may be aware that the bicentennial of Charles Darwin's birth is coming soon, on the 12th of February. This year is also the 150th anniversary of the first publication of On the Origin of Species.

2009 has been marked by the International Union of Biological Sciences (IUBS) as Darwin Year, and there are many celebrations and activities planned all over the world.

Biochemistry professor and prominent science blogger Larry Moran considers Darwin to be the greatest scientist who ever lived.

This is arguably true but that view will always be debated by supporters of other great scientists like Isaac Newton or Albert Einstein.

Personally, I have to admit that he is not my favourite scientist (Santiago Ramón y Cajal and Motoo Kimura come to mind) but I cannot dispute the immense impact of Darwin's discovery of natural selection.

Together with Alfred Russel Wallace, Darwin laid the early groundwork for evolutionary biology, which after years of correction and refinement by many other scientists, has gradually become the unifying concept in biology today.

This is a big change, not only within the confines of academia, but also in the wider society. With the understanding of common descent and incremental change, people now have access to greater insights into the detailed workings of Nature than ever before.

Take for example this salient question: "Why won't God heal amputees?"

That could have been a deep mystery two hundred years ago, since limb regeneration has never been observed in human beings but are possible in many other animals.

Salamanders can regenerate whole limbs, tails, parts of their hearts and even parts of their eyes.

Fish can regenerate much of their central nervous system, including the spinal cord.

And planarian worms can regenerate pretty much any part of their body - even their heads!

From a theistic perspective, especially for people who believe in an omnibenevolent God or Gods, this is very hard to explain.

Why would the Gods confer the "lowly" worms or fish such an amazing ability to recover from severe injuries, but yet not provide the same ability to human beings - who ought to be the centrepiece of creation?

The relative level of impairment is mindboggling; human beings cannot even regrow a finger, let alone an arm or a leg.

So many people had to endure a lifetime of pain, suffering and paralysis from lost limbs or broken backs. Ironically, many of them were soldiers who had fought so hard and so faithfully in the name of their Gods.

The odd thing is that people do have extensive regeneration capability in the liver, so it's not as if the Gods could not create this ability in human beings - certainly it wouldn't be a problem if they really were omnipotent.

So is this compelling evidence that the Gods are cruel and capricious?

Or maybe the Gods are giant transdimensional Worms, Fish or Salamanders? That would explain their bizarre love affair with these animals.

Since there were no other explanations available, in the past people could only hope and pray that someday their small request would be granted by the Gods and their limbs would grow back.

But that never happens. Perhaps the Gods work in mysterious ways.

With the advent of evolutionary biology however, the answer becomes crystal clear:

Human beings don't stand isolated as the centrepiece of special creation; they evolved from another species of animal in the past. Closely related species tend to share more common features than more distantly related species.

Our closest living relatives are the other great apes. Since none of them can regenerate limbs, it isn't surprising that humans also cannot do it.

In fact, no mammal can regrow a limb. That ability has been lost ever since our ancestors diverged from the ancestors of modern salamanders over 350 million years ago.

Thus you now have a systematic explanation that does not require the postulation of any good, evil or bizarre Gods, and saves you the stress and confusion of needing to know what they want. There is no need to beseech the Heavens for a cure either.

The only real solution is to build the replacement limbs ourselves, by learning more about regeneration from the animals that can do it, or by inventing robot limbs that mimick the function of biological limbs.











When you realize that no amount of hoping, praying or word twisting can regrow a missing limb; you will see why one can only understand Nature by scientific investigation, and why physical problems can only be resolved by physical solutions. The awareness of the irrelevance of supernatural "solutions" helps to spur efforts towards scientific discovery and technological innovation.

This, to me, is a vital implication of Darwin's legacy.


Would you like to know more?

- Review article: Why is limb regeneration possible in amphibians but not in reptiles, birds, and mammals? (Galis et al. 2003, Evolution and Development)

- Time Tree (a public knowledge-base that uses a hierarchical system to identify all published molecular time estimates bearing on the divergence of two taxa)