Feature: How Evolution Can Explain Allergies

Every summer, when I return home for my vacations, I am hesitant about eating food at roadside stalls because, you know, who knows how unhygienic the food there is? In a role reversal that I still find amusingly ironic, my mother would accuse me of being wimpy and shove a plateful of food into my hands. Her logic—if we are over-protective of our immune systems, they will ‘forget’ how to respond when hit by a major infection. Blood them in battle, she said.

I’m still going to hold off from the delicious and teeming-with-microbes sugarcane juice on Indian roads, but as it turned out my mother was on the right track. A variant of her statement does apply in the case of allergies in what has been proposed as the ‘Hygiene Hypothesis’. Did you know that the incidence of autoimmune diseases (allergies being a prime example of these) is much higher in industrialized countries? Exposure to infectious agents in childhood primes your immune system for a more effective immune response as you grow up. Conversely, an extremely sanitized environment (often seen in industrialized countries) during childhood can make your immune system weak, unprepared to face infections and respond to harmless molecules that then become allergens.

Evolutionary Mismatch

How, and why does this happen? The answer lies in an ‘evolutionary mismatch’. Our bodies evolved in an environment which is very different from the one we live in now.

Let’s travel back in time for a little bit. In the first stage of human history, members of our species were hunter-gatherers. Our immune systems were constantly being exposed to a host of microbial organisms and worms. Around 12,000 years ago, we started settling down and took to agriculture. We continued being exposed to microbes, and in fact the sedentary lifestyle led us to being exposed to them for longer periods and increased human-human transmission. And then came the Industrial Revolution, bringing with it sanitation, vaccines and the beginning of the world as we know it. Many of the organisms that our ancestors encountered on a daily basis are now depleted from our present-day environment.

[Image Credit: ucla/ Nature Immunology]

‘The Old Friends’ Hypothesis’

We have grown up in the industrial age, but our immune system has evolved over centuries in the first and second stages of human history. Microbes and worms were so omnipresent that our immune systems learned to tolerate their presence in the body if they were harmless. Reacting to an infection is costly for the body, as we know from the all-pervading weakness we experience after a fever. A wiser route for the immune system was to just let the microbe exist, and simultaneously, the worms evolved to release certain molecules that would down-regulate certain components of the human inflammatory system. In the current environment, our bodies do not contain the micro-organisms that regulated our immune system. Our immune systems thus rise to inflammatory baits in a heartbeat.

It’s still a hypothesis, but there’s plenty of evidence that supports it. Guts of children with allergies have been found to have fewer numbers of a bacterial species called lactobacillus. Another study in Argentina showed that people with fewer worms called helminths have fewer incidences of multiple sclerosis (MS).

Our bodies are thus not adapted to the environments we live in, leading to this kind of a mismatch. In context of public health, it is not feasible to think of returning to the environments of our ancestors, nor is it feasible to think of infecting allergic patients with 50 hookworms that would downregulate the immune response. However, learning more about the symbiotic  mechanisms between our ‘old friends’ and our immune systems could help design more effective therapies towards autoimmune disorders.

Sources:

Microbes, immunoregulation and the gut

Old Friends Hypothesis

How Parasites can trick your immune system

Mother-in-Law, Daughter-in-Law Conflict Led to Evolution of Menopause

One evolutionary quandary that has plagued biologists is the existence of a menopause in women—the time after which a woman loses her ability to reproduce. Why would females of a species stop reproducing? What is the evolutionary advantage to this? Wouldn’t it be better for a woman if she could keep producing offspring and thus propagating her genes for as long as possible? In fact, menopause is relatively uncommon in animals, though it has not been widely studied.

Grandmothering Effect and Other Hypothesis

One hypothesis that has been proposed to explain this is the aging effect. As women age, they are more likely to develop mutations that they pass on to their children. Stopping their ability to reproduce could help protect the species from defective mutations. Another hypothesis is the ’Grandmother effect’. If older women use their resources to help bring up existing off-spring instead of creating new ones, the additional resources given to a child increases its fitness.

A research team has used data from a pre-industrial Finnish population to test these hypotheses. Since the 17th century, the Lutheran church has collected a register of all births, deaths and marriages in Finland. The researchers had access to three generations of 5 Finnish populations.

This age-old conflict runs deep enough for evolution to have acted upon it! [Image Credit: towntopics]

Mothers-in-Law Compete with Daughters-in-law, But Not With Their Daughters

Their most interesting result was that when a mother-in-law and a daughter-in-law had children within two years of each other, their off-springs had significantly smaller lifespan by up to 66%. This suggests that competition between in-laws have led to menopause evolving as an adaptation. On the other hand, when a mother-daughter pair had children within two years of each other, no reduction in children’s ages were seen.

A woman shares no genes with her daughter-in-law, and her grandchild only shares 1/4th of her DNA as opposed to her child (which has ½ of her DNA). Thus, there is no co-operation between the two during child-rearing leading to reduced fitness of all the off-spring. It is interesting to note the contrast when mother-daughter pairs bear children simultaneously and show no competition. The authors suggest that in-laws fought over resources for their children instead of co-operating as mothers and daughters might do.

Modeling this data, the authors of this research have proposed a combination of factors that lead to the evolution of menopause. The first is the grandmother effect, and the second is the avoidance of reproductive conflict between mothers-in-law and daughters-in-law.

You can read about this research here.

Suspected: Insects Undergoing Some Kind of Photosynthesis

The gardener’s nightmare might be the entomologist’s goldmine. Among the most destructive of all insects are small sap-sucking critters, called Aphids. They are very populous, reproducing via both sexual and asexual means, and are difficult to eliminate using pesticides. Aphids are also colored insects. They generally have a green color, but can also acquire a red color as they can also synthesize red carotenoids (pigment proteins). They are the only animals known to be able to synthesize pigments.

Aphids (Photo Courtesy: University of California)

A process similar to photosynthesis

What wasn’t known was that aphids can actually use these pigments to metabolize using sunlight, much the same way that plants do! Yes, aphids can undergo a process similar to photosynthesis in plants, finds a group of researchers.

This startling finding is due to a group working under entomologist Alain Robichon at the Sophia Agrobiotech Institute in Sophia Antipolis, France. The group worked with green, orange and white aphids. White aphids are found where resources are scarce and they are almost completely devoid of pigments. Green aphids are found in places with cold temperatures, but still enough food to go around.

Counting ATP

The group measured the ATP levels in the aphid bodies. ATP is the ‘energy currency’ of the living organism – this is the molecule that is transferred between cells when an energy transfer has to occur. The results of the measurements were astounding: Carotenoid rich green aphids registered a much higher level than the white carotenoid-devoid ones, suggesting that the green pigment might be instrumental in providing another source of energy production.

Look at the two lines. They represent the optical density (OD), indicative of the ATP/metabolic activity of the pigment. Clearly the green pigment (represented by the solid black line) has higher absorption at all wavelengths.

Moreover, when the orange aphids – containing moderate amounts of carotenoids – were placed in sunlight, they showed intermediate levels of ATP. Interesting. Very interesting indeed.

Not the photosynthesis we know

One has to note that this ‘photosynthesis’ merely refers to the use of sunlight in order to gain energy. This doesn’t refer to the photosynthetic process that goes on in plants, which require the transfer of a positive charge from a water molecule, leading to the expulsion of oxygen (and thus we breathe!). Also, carbon dioxide has not been shown to be essential to the aphids version of the photosynthetic process.

The carotenoid molecules are placed about 0-40 micrometers deep under the cuticle, making them perfect to capture both the incident and the transmitted solar radiation.

Questions, questions

But questions remain – why should the aphids need to synthesize? As mentioned above, aphids in high food resource areas develop strong pigmentation and can also synthesize food for themselves. But doesn’t that defeat the very purpose? Why make when you already have food?

Both the mechanism and the necessity are unclear. These tiny critters had an unknown ace up their sleeves and there might be more.

The paper: http://www.nature.com/srep/2012/120816/srep00579/pdf/srep00579.pdf

Mysterious Island of Pumice Spotted on the South Pacific

Sheets of pumice forming a giant floating island have been spotted in the South Pacific. The size of the island is larger than the entire area of Israel. The whole island is 480 kilometers in length and about 50 kilometers in width. The New Zealand Royal Air Force spotted the floating pumice raft southwest of Raoul Island.

A screenshot from the youtube video uploaded by the NZ Air Force (see below) Courtesy: Youtube

Pumice and how it forms

Pumice is made from lava which cools off too fast. The trapped air pockets in the rocks makes it both porous and buoyant. An underwater volcano could’ve created this gigantic pumice island. A possible candidate is the Monowai seamount, along the Kermadec arc which has been active in recent times. The sheet reportedly looked like a giant floating icesheet.

Samples of the pumice float have been collected by at least two research groups, one of them being Australian government supported. These will help answer the question as to where these come from.

Here is a Youtube video uploaded by the New Zealand Royal Air Force:

How pumice is related to the very origin of life

Interestingly, pumice rocks and pumice sheets are not just an interesting artifact. They might be vital to life on the planet as we know it! Pumice rocks could’ve provided nice habitat for early Earth microbes. They could cling on these and populate themselves.

Further, chunks of pumice could’ve ferried animals across vast stretches of water, maybe hop islands! Remote islands could’ve been seeded like this, which then evolved uniquely, giving rise to insular populations of animals not seen anywhere else in the world. So pumice may have been the substrate on which life formed and also a mode of transport for developed life forms!

Yes, science does hold a lot more mysteries than dreamt of in your philosophy, my Horatio!

Fossils Point to Multiple ‘Homo’ Species

Fossil Questions if Our Ancestors Had Cousins

There exists a fossil of a human skull, labelled 1470, which has been at the center of quite a bit of controversy since its discovery in 1972. This fossil, said to be from 2 million years ago, was different enough from the existing human ancestor at that period—Homo erectus—for some scientists to propose that it belonged to a new species. And thus were formed two warring camps. One said that 1470 belonged to Homo erectus, and the difference could be accounted for by variation within a species. The other camp believed that 1470 represented a remnant of a new species that might have existed along with Homo erectus, meaning that the lineage of current humans might not be as linear as we think it is.

A timeline in Homo sapiens evolution. Homo rudolfensis is the contested species which might have co-existed with two others.
A timeline in Homo sapiens evolution. Homo rudolfensis is the contested species which might have co-existed with two others. [Image Credit: Nature]

Now, the discovery of three new fossils has strengthened the claims of the second camp. These were discovered by a team led by Meave Leakey (who was also involved in discovering 1470) also near Lake Turkana in Kenya. The new fossils, which are from 1.78 to .95 million years ago, resemble fossil 1470 in skull structure by having similarly large and flat faces. Scientists are saying that the presence of more than a single outlier suggests that 1470 wasn’t just an unusual case in the species Homo erectus, but just one among a number of individuals in an altogether new species, which they are calling Homo rudolfensis. This finding contradicts the belief that our species evolved from the ancestors we share with apes in a strictly linear progression. The authors of this research believe that 3 species existed simultaneously—erectus, 1470 and a third branch— of which erectus eventually evolved to become Homo sapiens.

Not Definitive Evidence

This discovery isn’t convincing the critics, though, who think the evidence is not definite, and that the three fossils could still be diverse members of the same species. For now, our family tree remains murky.

You can unearth more information about this research here and here.

Ancient Snake Fossil Identifies Snake Ancestry

Biologically, snakes are just glorified lizards. Glorified, they are, for a reason. There are around 3000 species of snakes in a variety of habitats. Together, they form one of the most successful groups in the animal kingdom.

Did Snakes Evolve on the Land or in the Sea?

Where did snakes evolve from? Did they arise from marine environments, as their bodies became more slender in an adaptation for swimming, or did they arise from terrestrial environments, in which case their bodies would have become adapted for burrowing? Also, snakes have remarkably flexible jaws which allow them to devour prey much larger than themselves. Chances are that you haven’t come across any pictures of lizards ingesting huge animals. This is because lizards have inflexible jaws. How, then, did snakes get these jaws when their cousins don’t have them?

We don’t know the answers to these questions because of the incomplete fossil records in the serpent lineage. There haven’t been any fossils that connect snakes and lizards. Now, a snake fossil forming the missing link between these two classes of reptiles has been found.

Jaws of lizards (a), Coniophis (b) and modern snakes (c). Coniophis has hooked teeth like modern snakes, but its skull is still fixed. [Image Credit: Nicholas Longrich: taken from the publication in Nature]

New Snake Fossil Provides Perfect Snapshot of Evolution

Coniophis precedens from the plains of North America represents one of the most primitive snakes. Based on species comparison (also called ‘phylogenetic analysis’) with other snakes, it has been found to be amongst the most ancient. In what is a perfect snapshot in the evolutionary process, it has a snake-like body and a lizard-like head with snake-like teeth. Its small size and reduced spines both point to it being fossorial—adapted for digging. This points us towards snakes having evolved from burrowing lizards, and not from marine environments. Its hooked teeth, like those of its contemporary kin, are suitable for chewing on relatively large, soft-bodied prey, but like lizards, its jaw remains relatively fixed. Its slender body enabled it to slither, and according to Professor Nicolas Longrich, who headed this study, it could have slithered “beneath the feet of the dinosaur Tyrannosaurus rex”.

The picture that emerges is that Coniophis was a small carnivorous land snake that preyed upon small vertebrates. Snakes that followed it evolved flexible jaws in a series of adaptations that enabled them to feed on a greater variety to prey. Coniophis thus represents a stage in the stepwise accumulation of adaptations.

The bones of this ancient and important connecting link in the evolution of snakes are in museum collections in the United States of America.You can read more about this research here.

Scientists Create Silicone Jellyfish From A Rat’s Heart Muscle

Yes, there might be protests as scientists are ‘playing God’ again, but the news is too exciting to stoop to such petty protests. Scientists have mimicked the movement of a mammalian heart and made an artificial jellyfish, which can swim using the exact movements that the heart undergoes when it pumps blood. The body of the jellyfish is made up of silicone with cardiac tissue from a rat mounted on this scaffolding.

The Medusoid

Heart and the Jellyfish

The researchers from Harvard University and California Institute of Technology (Caltech) noticed the similarities between the pumping motion of a heart and the pumping motion that helps a jellyfish swim. This is the latest in the emerging field of synthetic biology. Says Kevin Kit Parker, one of the people involved in the study:

I started looking at marine organisms that pump to survive. Then I saw a jellyfish at the New England Aquarium and I immediately noted both similarities and differences between how the jellyfish and the human heart pump.

And thus was born ‘Medusoid’. The main challenge was the lack of understanding of how the heart muscles actually co-ordinate themselves via electrical signals. Then they performed something called ‘reverse engineering’. To understand how a medusa jellyfish really swims and how the muscles are all co-ordinated, the team used techniques from biometrics and crystallography. They were also able to understand the exact biomechanics of the propelling muscle contractions.

Mimicking as much as possible (Taken from the paper)

Getting everything to work together

It turns out that the mammalian heart muscles move in much the same way when they pump blood. Thus, the plan was to make the jellyfish out of cultured cardiac tissue taken from a rat. Silicone would provide the scaffolding that the structure needed. Then they matched the Medusoid with a real medusa jellyfish, part by part. They made sure that the Medusoid was a copy as long as cellular architecture went.

Cellular architecture has to match – and they do!
(Taken from the paper)

Less tricky was the design of the silicone structure. They had to ensure that the structure pushed water efficiently, like the jellyfish has evolved to do. Too much gap between the ‘legs’ and water would just ‘leak’ through. Too little and you’d just be wasting precious power for thrusting. The cardiac muscles were stimulated by electrical signals.

The work has been reported in Nature Biotechnology in this paper. Lead author of the paper is Janna Nowroth, a research student. His PhD advisor John Dabiri, an expert of biopropulsion is also an author of the paper. Kevin Kit Parker, another coauthor, is an expert in the field of tissue engineering. He had created artificial ‘organisms’ that can grip and pump. The jellyfish was really ambitious!

So what’s the next step? Endowing the jellyfish with something that even it doesn’t have – a brain. The team wants to put a small control center for the nerves so that it can decide where it wants to go.

Additional infohttp://www.nature.com/news/artificial-jellyfish-built-from-rat-cells-1.11046

Found: The Most Complete 2-Million Year Old Human Fossil in the ‘Cradle of Humankind’

The dead do speak. And it is the paleontologists who go around trying to eavesdrop on such a silent conversation. Most of the times, the sentences are broken. Once in a while, a whole sentence is found and much jubilation follows. One of these sentences, which I use as an euphemism for ‘skeletons’ here, has been found in the so-called ‘Cradle of Humankind’, north of Johannesburg. The question: what does it really say?

The skull of the A.sediba individual. Look at the white spot on the rock – that’s the hominid tooth.

Where the individual fits – in space and in time

The skeleton, nestled lightly between hard rock, is a hominid skeleton and is the “most complete early human ancestor skeleton ever discovered”. It is about 2 million years old, which puts it right at the beginning of the time when the species of the genus Homo – whose members walked on two legs and had less hair than the apes – were beginning to emerge. The oldest known members of the Homo genus are Homo habilis, whose skeletons date back to 2.3 million years ago. Homo erectus, the first species of the Homo genus, to walk upright emerged later around 1.6 million years ago.

The skeleton is that of Australopithecus sediba species. It is widely believed that one of the species of the Australopithecus genus evolved to give the Homo genus, which leads to us. One of the species is our ancestor. A. sediba is probably not!

Skeleton – such a completeness was never there before

The skeleton reveals that the individual was learning to walk upright, fitting right into that snug spot on the evolutionary ladder between becoming merely bipedal and becoming bipedal and upright. The individual is an infant aged between 9 and 13 years and it could be of either gender. This is actually the completion of an expedition that revealed part of this same fossil way back in 2009.

Prof. Berger, a lead scientist in this expedition is thrilled:

We have discovered parts of a jaw and critical aspects of the body including what appear to be a complete femur [thigh bone], ribs, vertebrae and other important limb elements, some never before seen in such completeness in the human fossil record.

The discovery was a stroke of luck, it seems. The team spotted a piece of hominid tooth embedded in black stone. They excavated further to reveal a complete skull!

Questions?

The critical question remains: was A.sediba a direct ancestor to us? The skeleton hasn’t started singing out its secrets yet. It will soon!

The Cradle of Humankind, as romantic and innocent as it might sound, is actually a deep pit containing many caves, where a large number of individuals of A.sediba and some other species are had fallen and died. For scientists studying human origins, this is a goldmine. The site has been the continuous paleontology site and has now been declared a World Heritage Site.

Now, just to wait to hear the dead speak…

Editorial: Creation vs. Evolution and the Fear That Drives Both

In 1859 Charles Darwin turned the world on its side by publishing the book On the Origin of Species. This book outlined his observations on evolution and introduced the concept known as natural selection. Darwin’s theories have since gained wide acceptance in the scientific community and have laid the foundation for evolutionary biology. His theories have also been used to drive a solid wedge between the religious and scientific communities. This unfortunate result can be seen playing out even today as my esteemed colleague, Debjyoti Bardhan, points out in his article “South Korea’s Scientists Strike Back At Creationism; Force Withdrawal of Omission of Evolution“. To me the fundamental problems at the heart of this debate are that of power, fear, and lack of mutual respect.

Origin of Species
(Courtesy Wikipedia)

He Didn’t Start the Fire

Contrary to the noise you hear on both sides of the creation vs. evolution debate, Darwin didn’t set out to stick it to Christians when he published his theories. Some may be surprised that early in Darwin’s life, he actually considered going into the clergy. As a matter of fact, Darwin struggled with his thoughts on God his entire life and in a letter to John Fordyce he proclaimed, “It seems to me absurd to doubt that a man may be an ardent Theist & an evolutionist.” But the fire that burned between science and the church started long before Darwin’s time. One could point to the debate between Galileo and the Roman Catholic Church. Galileo correctly observed that the earth was not the center of the universe. He supported the heliocentric view meaning the earth was just a planet that circled the sun. This view got him in a lot of heat with the Roman Catholic Church. His views were deemed heretical and didn’t agree with church authorities of that day. Unfortunately for him, he didn’t have the tools he needed to really prove his argument. On the flip side, Galileo wasn’t entirely correct either. The sun was the center of our solar system however, as we know now it was not the center of the universe.

All of this history reminds me of the saying “Power tends to corrupt, and absolute power corrupts absolutely.” One of the things I observe in this whole debate is that both parties involved seem to get drunk with power. Nothing is more unbecoming of science than when scientists wield their power and influence to push a social or political agenda. How many studies have I seen lately funded by some special interest group with the “surprising” result that the “scientific” conclusion agrees with those of the group. In the same line of thought, nothing can be more opposite of the life that Jesus lived than these so called “Christians” who would threaten the very lives of scientists with whom they do not agree.

South Korea’s Scientists Strike Back At Creationism; Force Withdrawal of Omission of Evolution

It’s being called a ‘reconsideration’ by the conservative media, but it is actually no less than a big victory. Throughout most of the Christian world, creationism is increasingly making its presence felt in the school curriculum. And this worrying trend has spilled out of the United States and entered other countries, the latest victim being South Korea. However, this is one country that is recognising the evil and trying to nip it in the bud.

No longer there? Think again!

On the 5th of June, Nature reported here that creationism is getting strong support in the country and the movement was forcing publishers into removing evolution related content from the school textbooks. Of the most seminal expunging carried out, notable mention must be made of Archeopteryx and of the evolution of the horse. Apparently, the evolutionists were not consulted before this decision was taken.

“Deleting” an “error”

Principal player in this campaign of deleting the “error” of evolution in a bid to “correct” students was the Society of Textbook Revise (STR), an offshoot of the Korean Association for Creation Research. It also suggests major changes about known and proven theories of evolution of humans and other species.

Come July, and the evolutionists have scored a major victory. Nearly 50 prominent Korean scientists are presenting a petition to the government officials rejecting the proposed changes before they enter the textbooks. Leading the fightback is an insect taxonomist Byoung-Hoon Lee. What has been promoted as “atheist materialism” by the STR is nothing but hard scientific fact, argues the scientist side.

The Richard Dawkins of Korea

The Richard Dawkins of Korea, as he is popularly called, Jae Choe, an evolutionary biology, has been Darwin’s faithful bulldog in this peninsular nation. He is hopeful, – no, confident really – that this will yield a result.

When these things are done, I think it will turn out that after all Korean science will not surrender to religion, so to speak.

The problem was with the scientific community as well, as they allowed such nonsense to be propagated. But the situation hasn’t gone out of hand. Choe says:

After all this hoopla, it looks as if South Korea will not ‘surrender’ to creationist demands.

That is good news.

The creationist side will not go down without a fight, though. They promise to fight on till every example of evolution is wiped out. And they have God on their side, so a win is on the cards, right?

Well, Choe and other scientists differ. And at the moment, fortunately, they seem to be very correct.