The Friends of Charles Darwin

Adult swallow feeding it young.

It's getting to be what the locals around here refer to as a little back-endish—by which they mean summer is on its way out, and autumn approaches.

Returning to my house today, I spotted several swallows congregating on the nearby telephone wires. At this time of year, this is a clear sign that they are preparing to migrate south for the winter. As they appeared to be fairly settled, I grabbed my camera and walked back down the hill to fire off a few photographs. It turned out that the swallows on the telephone wires were recently fledged juveniles, who were waiting to be fed. I watched for ten minutes or so as their parents gathered flies over the adjacent fields and returned to feed their young.

By coincidence, I am currently reading Richard Mabey's biography of the famous Eighteenth Century naturalist, Gilbert White (Amazon UK), who was an early influence on Darwin. White was fascinated by swallows. Their annual appearance in spring and disappearance again in late summer was still a mystery during his lifetime. In February, 1769, he wrote to his friend, Thomas Pennant:

When I used to rise in the morning last autumn, and see the swallows and martins clustering on the chimnies and thatch of the neighbouring cottages, I could not help being touched by a secret delight, mixed with some degree of mortification: with delight to observe with how much ardour and punctuality those poor little birds obeyed the strong impulse to migration, or hiding, imprinted on their minds by their great Creator; and with some degree of mortification, when I reflected that, after all our pains and inquiries, we are yet not quite certain to what regions they do migrate; and are still farther embarrassed to find that some do not actually migrate at all.

To his dying day, White never did find out for certain whether swallows migrated or hid (by which he meant hibernated). We now know that swallows migrate from Britain to South Africa during our winter: a phenomenal journey for such a small bird. And we now know that this impulse to migration is not imprinted on their minds by a creator, but by evolution.

Darwin was right: there is grandeur in his view of life.

I appreciate I'm probably being a bit unfair quoting from a brief news article, but is this a total non-story or what?

BBC: Study uncovers 'chimp cross code'

Experts studying chimpanzees while investigating the evolution of human social behaviour have uncovered their ability to safely cross roads.

They said the discovery has shown chimps' ability to cope with the risk of man-made situations…

It found the dominant adult males took up protective positions in the group when it was tasked with crossing roads…

The study has built on prior research showing that adult male monkeys took similar action to reduce the risk of being attacked by predators when travelling towards potentially unsafe areas, such as waterholes.

Kimberley Hockings, who worked on the study, said: "Road-crossing, a human-created challenge, presents a new situation that calls for flexibility of responses by chimpanzees to variations in perceived risk, helping to improve our understanding about the evolution of human social organisation.

In other words, what they appear to be saying is that, when presented with an unusual and/or potentially dangerous situation, dominant male chimps and monkeys take protective positions in front of and behind the group. An interesting, if pretty unsurprising observation.

But why do the people carrying out the study think that road-crossing presents a new situation that calls for flexibility of responses? Aren't the chimps simply giving a perfectly normal response when presented with a potentially risky situation? And why on earth do they think this is going to teach us anything about the evolution of human social behaviour? Don't loads of other animals (elephants, for example) do exactly the same thing?

I'm sure we can make certain inferences about the evolution of human behaviour by studying chimps, but I can't help feeling people read far too much into such studies. Why not study the chimps for their own sakes, rather than trying to bring in pretty tenuous links to human behaviour?

BBC: Attempt to save declining lapwing

A five-year project has been launched to halt the decline of the lapwing, a bird traditionally known as the "farmer's friend".

More than 250 farm sites have been chosen to test measures designed to help the species recover.

Lapwing numbers have declined in the UK by almost 50% since 1970.

The article goes on to explain that the decline is believed to be due to modern farming practices, such as the loss of mixed agriculture, and the draining of land. This may well be correct, but I think there might be another reason, also linked with changes in farming practices:

I live in the South Pennines. Lapwings are one of my favourite birds. A pair of them nests in the fields behind my house every year. I have spent many an hour watching them from afar, and would be truly amazed if they have ever managed to rear a brood successfully. The reason: carrion crows. There are hundreds of them in these parts, and the poor lapwings seem to spend the whole of the nesting season fighting them off. I can't believe any of the eggs/chicks survive the onslaught. Indeed, I was talking to someone about it only last week, and he said that, this summer, he witnessed a carrion crow flying off with a young lapwing chick.

And why are there suddenly so many carrion crows? I would guess it's because so few farmers are shooting them any more. The laudable clampdown on firearms in recent years, and the public's disapproval of shooting birds have meant, I would hazard a guess, that crow numbers have increased in recent years, with disastrous consequences for lapwings.

Well, that's my theory at least, and I'm sticking to it.

A crane fly on my window last week

It's crane fly season here in West Yorkshire. Last week, we were suddenly inundated with them. One week there wasn't any sign of them, the next they were all over the place—particularly in the evenings.

I didn't know, until I looked it up, that crane flies spend most of their lives underground in their larval forms, which are known a leatherjackets. I knew that leatherjackets were very common round here, and are a favourite food of the local crows (particularly the rooks), but I did not know that leatherjackets transform into crane flies. You learn something every day.

I naturally supposed that crane flies emerge en masse to increase their chances of encountering a mate—which I still guess is right. But then I had another thought: emerging en masse will also give the individual crane flies a better chance of avoiding being eaten by predators: plenty more fish in the sea, so to speak. And then it occurred to me that they emerge in early September, which is about the time that swallows traditionally start heading south for the winter. Could the timing of the crane flies' emergence in September be an adaptation to avoid being eaten by swallows?

If so, it isn't a 100% reliable strategy. One evening last week, a family of swallows spent a good half-hour hunting around the west-facing eaves of my house. I initially mistook them for local bats—I had not seen swallows that close to the house before. I wonder if they were hunting crane flies, which appear to be attracted to the residual warmth of the building after sunset.

Darwin would have loved this:

BBC: Channel's key role in pre-history

A study of prehistoric animals has revealed the crucial role of the English Channel in shaping the course of Britain's natural history. The Channel acted as a filter, letting some animals in from mainland Europe, but not others.

Even at times of low sea level, when Britain was not an island, the Channel posed a major barrier to colonisation. This was because a massive river system flowed along its bed…

"We find we're getting only a selection of the mammals during the British interglacials that there are in mainland Europe," said Professor Stringer [of London's Natural History Museum]. "For example, at one pre-historic site, researchers found hippopotamus and fallow deer; but unlike mainland Europe at the time, there were no horses and no humans. This suggests that the Channel, or the Channel river system, is acting as a filter to prevent the movement of some of these [mammal] forms into Britain."

Colonisation of islands was a subject of great importance to Darwin. He devoted chapters 11 and 12 of Origin of Species to the geographical distribution of species, and islands figured heavily in his theories of speciation. He was mainly interested in mid-ocean islands, such as the Galapagos Islands, but he was always on the lookout for examples of how species could become isolated from parent stock.

I was contacted by the UK Woodland Trust charity today, who wanted to draw my attention to their urgent campaign to purchase land to buffer and extend the ancient woodland of Blackbush Shaw near Darwin's home in Kent. The woods form part of the natural landscape from which Darwin sought inspiration while he was forming his theory of evolution. Darwin's great great grandson, Randal Keynes OBE is the project's official patron.

The Trust has an opportunity to extend, buffer and safeguard Blackbush Shaw for generations to come. But they have less than two months to raise the £250,000 needed to buy and manage the plot, and an urgent fundraising appeal has been launched.

If you would like to help this worthy cause, you can (as I am about to do) make an online donation to the Woodland Trust here.

Another so-called missing link rises from the dust:

BBC: 'Lucy's baby' found in Ethiopia

The 3.3-million-year-old fossilised remains of a human-like child have been unearthed in Ethiopia's Dikika region.

The female Australopithecus afarensis bones are from the same species as an adult skeleton found in 1974 which was nicknamed "Lucy".

Another example of Darwin's being well ahead of the game:

BBC: British species migrate northward

Right across Britain, animals are on the march, moving northwards and going to higher ground as the climate warms, experts have told a major conference…

Chris Thomas from the University of York said the changes fitted neatly with the predictions of climate models. "Species are moving north, they're climbing mountains, they're retreating at their southern boundaries," the professor added.

Compare the above with the situation at the end of a former glacial period, as envisaged by Charles Darwin in chapter 11 of Origin of Species:

As the warmth returned, the arctic forms would retreat northward, closely followed up in their retreat by the productions of the more temperate regions. And as the snow melted from the bases of the mountains, the arctic forms would seize on the cleared and thawed ground, always ascending higher and higher, as the warmth increased, whilst their brethren were pursuing their northern journey. Hence, when the warmth had fully returned, the same arctic species, which had lately lived in a body together on the lowlands of the Old and New Worlds, would be left isolated on distant mountain-summits (having been exterminated on all lesser heights) and in the arctic regions of both hemispheres.

True, unlike in Darwin's scenario, we aren't emerging from an ice age, but the principle is the same: our climate is getting warmer and species are on the move. Exactly as Darwin predicted.

Woot! In Our Time is back on Radio 4, and the first programme in the new series was about Darwin's great hero, Alexander von Humboldt:

• Download MP3 file
(only available for one week, I think)
• Listen again (permanent archive in crappy Real Audio player format)
• In Our Time Podcast RSS feed

One for the morning commute tomorrow.

It's fascinating to think that the evolution of life on earth might have been affected by an increase in eroded minerals brought about by the creation of a huge mountain range:

New Scientist: Mega-mountains spurred explosive evolution

A continental crash that raised one of the biggest mountain chains in the Earth's history may be responsible for the explosive diversification of animals more than 500 million years ago.

Sediments washed from the mountains—dubbed the Transgondwanan Supermountain—added vital nutrients to the ocean, opening new evolutionary opportunities, says Rick Squire, now at Monash University in Clayton, Victoria, Australia.

The rapid proliferation of animals that occurred at that time is one of evolution's biggest enigmas. Life had remained simple and largely single-celled for nearly three billion years, until the multi-celled Ediacara fauna evolved, 575 million years ago.

Most major groups of animals evolved during a second radiation, called the Cambrian explosion, from 530 to 510 million years ago. The mystery of what suddenly kick-started animal evolution has been a topic of hot debate among experts.

Other people have suggested that changes in wind patterns brought about by the creation of the Himalaya, when the Indian sub-continent collided with Asia, could have given Africa a drier climate, making forests give way to savanna, and forcing our primate ancestors to come down from the trees.

Mountain formation was a subject of great fascination to Darwin. Indeed, during the Beagle voyage, he uncovered masses of evidence that South American was gradually rising. He also reasoned that a corresponding drop in the bedrock of the surrounding oceans suggested a mechanism for the creation of coral reefs. As usual, Darwin was right, but it wasn't until the 1960s that scientists devised theories of plate tectonics to explain the movements.