̽��ֱ�� of Cambridge - hunting

Pledge to phase out toxic lead ammunition in UK hunting by 2025 has failed

jg533 — Thu, 06 Mar 2025 09:14:35 +0000

̽��ֱ��pledge, made in February 2020 by the UK’s nine leading game shooting and rural organisations, aimed to benefit wildlife and the environment and ensure a market for the healthiest game meat food products.

But a Cambridge team, working with the ̽��ֱ�� of the Highlands and Islands, has consistently shown that lead shot was not being phased out quickly enough to achieve a complete voluntary transition to non-toxic ammunition by 2025. In a final study, published on 6 March in the journal Conservation Evidence, the team concludes that the intended transition has failed.

̽��ֱ��team has closely monitored the impact of the pledge every year since its introduction, recruiting expert volunteers to buy whole pheasants from butchers, game dealers and supermarkets across Britain and recover embedded shotgun pellets for analysis.

In 2025, the study - called SHOT-SWITCH - found that of 171 pheasants found to contain shot, 99% had been killed with lead ammunition.

This year, for the first time, the team also analysed shotgun pellets found in red grouse carcasses shot in the 2024/25 shooting season and on sale through butchers’ shops and online retailers. In all 78 grouse carcasses from which any shot was recovered, the shot was lead.

“Many members of the shooting community had hoped that the voluntary pledge away from lead ammunition would avert the need for regulation. But the voluntary route has now been tested - with efforts made by many people - and it has not been successful,” said Professor Rhys Green in the ̽��ֱ�� of Cambridge’s Department of Zoology and lead author of the report.

Eating game meat killed using lead shot will expose people unnecessarily to additional dietary lead. Lead is toxic to humans even in very small concentrations; the development of the nervous system in young and unborn children is especially sensitive to its effects. As a result, many food safety agencies now advise that young children and pregnant women should avoid, or minimise, eating game meat from animals killed using lead ammunition.

Discarded shot from hunting also poisons and kills many tens of thousands of the UK’s wild birds each year.

Despite proposing the voluntary change, many shooting organisations and some individual shooters do not support proposed regulatory restrictions on lead ammunition.

Green said: “Private individuals pay a lot of money to shoot pheasants on some private estates - and people don’t like to change their habits. It’s a bit like wearing car seatbelts, or not smoking in pubs. Despite the good reasons for doing these things, some people were strongly against using regulation to achieve those changes, which are now widely accepted as beneficial. ̽��ֱ��parallel with shooting game with lead shotgun ammunition is striking.”

Danish shooters now say that the legal ban on lead introduced in Denmark around 30 years ago was justified. They say it has not reduced the practicality or popularity of their sport, and has increased its acceptability to wider society.

“Although a few large UK estates have managed to enforce non-lead ammunition on pheasant shoots, some have had to be quite draconian in order to do it, with the estate gamekeepers insisting on loading the guns for the shooters,” added Green.

In the 2020/21 and 2021/22 shooting seasons, over 99% of the pheasants studied were shot using lead ammunition. This figure dropped slightly to 94% in 2022/23 and 93% in 2023/24, with the remaining pheasants killed by ammunition made of steel or a metal called bismuth, before rising to 99% again in 2024/25.

Retail pressure

̽��ֱ��researchers also checked up on a pledge made by Waitrose in 2019 to stop selling game killed with lead ammunition.

They found that the retailer had been largely let down by suppliers, and that some of their shooters continued to shoot using lead despite making assurances to the contrary. As a result, Waitrose did not sell oven-ready pheasants at all between 2021 and 2023. It sold pheasants again in January 2024 and the 2024/25 season, but the researchers showed that the majority had been killed using lead shot.

In 2022 the National Game Dealers Association (NGDA), which buys game and sells it to the public and food retailers, also announced it would no longer sell game of any kind that had been shot using lead ammunition. But this pledge has since been withdrawn. ̽��ֱ��researchers bought 2024/25 season pheasants from three NGDA member businesses and found that all had been shot with lead ammunition.

Inside influence

̽��ֱ��researchers also analysed all articles relating to the voluntary transition published in the magazine of the UK’s largest shooting organisation, the British Association for Shooting and Conservation. They found that articles near the beginning of the five-year pledge communicated clear, frequent and positive messages about the effectiveness and practicality of non-lead shotgun ammunition.

But by 2023, mentions of the transition and encouragement to follow it had dropped dramatically.

̽��ֱ��upshot

At the request of the Defra Secretary of State, the UK Health & Safety Executive (HSE) has assessed the risks to the environment and human health posed by lead in shot and bullets. Its report, published in December 2024, proposes that the UK Government bans the use of lead shot and large calibre bullets for game shooting because of the risks they pose to the environment and health. This recommendation is currently under review by Defra ministers, with a response due in March 2025.

Steel shotgun pellets are a practical alternative to lead and can be used in the vast majority of shotguns, as can other safe lead-free alternatives. But the results of this study indicate UK hunters remain unwilling to make the switch voluntarily.

Since 2010, UK governments have preferred voluntary controls over regulation in many areas of environment and food policy and have suggested that regulation be used only as a last resort.

“Shooting organisations did a lot of questionnaire surveys when the pledge was introduced in 2020, and the results suggested many shooters thought the time had come to switch away from lead ammunition. Those responses stand in contrast to what we’ve actually measured for both pheasant and grouse,” said study co-author Dr Mark Taggart at the ̽��ֱ�� of the Highlands and Islands.

Toxic lead

A previous study led by Green and colleagues found that pheasants killed by lead shot contained many fragments of lead too small to detect by eye or touch, and too distant from the shot to be removed without throwing away a large proportion of otherwise useable meat. This means that eating pheasant killed using lead shot is likely to expose consumers to raised levels of lead in their diet, even if the meat is carefully prepared to remove whole shotgun pellets and the most damaged tissue.

Lead has been banned from use in paint and petrol for decades. It is toxic to humans when absorbed by the body and there is no known safe level of exposure. Lead accumulates in the body over time and can cause long-term harm, including increased risk of cardiovascular disease and kidney disease in adults. Lead is known to lower IQ in young children and affect the neurological development of unborn babies.

̽��ֱ��studies were part-funded by the RSPB, Waitrose & Partners, and an anonymous donor. They were supported by a group of unpaid volunteers, who are co-authors of the reports.

References

Green, R E et al: ‘ ̽��ֱ��proportion of common pheasants shot using lead shotgun ammunition in Britain has barely changed despite five years of voluntary efforts to switch from lead to non-lead ammunition.’ March 2025, Conservation Evidence. DOI: 10.52201/CEJ22/EXYS6184

Green, R E et al.: ‘Sampling of red grouse carcasses in Britain indicates no progress during an intended five-year voluntary transition from lead to non-lead shotgun ammunition.’ February 2025, Conservation Evidence. DOI: 10.52201/CEJ22/YYWM1722

A voluntary pledge made by UK shooting organisations in 2020 to replace lead shot with non-toxic alternatives by 2025 has failed, analysis by Cambridge researchers finds.

̽��ֱ��voluntary route has now been tested - with efforts made by many people - and it has not been successful.

Rhys Green

Andy Hay, RSPB

Adult pheasant

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Birds of prey populations suppressed by lead poisoning from gun ammo

fpjl2 — Wed, 16 Mar 2022 12:48:49 +0000

New study uses data on lead levels in the livers of thousands of dead raptors to calculate the impact of lead poisoning on population size.

Managed hunting can help maintain animal populations

sc604 — Mon, 21 May 2018 09:56:35 +0000

̽��ֱ��international team of researchers, led by the ̽��ֱ�� of Cambridge and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), studied the hunt of Alpine ibex – a type of wild goat with long, curved horns – in the eastern Swiss canton of Graubünden by examining the horn size of more than 8,000 ibex harvested between 1978 and 2013, to determine whether average horn growth or body weight had changed over the last 40 years.

Their results, published in the Journal of Animal Ecology, reveal that unsurprisingly, ibex with longer-than-average horns are more likely to be shot than animals of the same age with shorter horns. However, due to tight controls placed on the hunt by the Swiss authorities, hunters tend to shoot as few animals as possible, to avoid violating the rules and incurring large fines.

Hunting for specific traits can place selective pressure on certain species, resulting in a negative evolutionary response. In their study, the researchers investigated whether the targeting of ibex with large horns would lead to a lower average horn size across the entire population.

They found that while even tightly-managed hunts cannot prevent hunters from targeting longer-horned animals, no long-term changes were found in the horn length of male ibex in Graubünden, which is most likely related to the fact that the numbers of ibex removed from the population by hunters is too small to have an evolutionary effect.

“Our most important finding is that ibex hunting over the last 40 years has not had a negative effect on the constitution of the animals,” said WSL’s Kurt Bollmann, the study’s senior author.

“ ̽��ֱ��good news for hunting and nature conservation is that horn growth in Graubünden’s ibex has not reduced over the decades and their average body weight has also remained stable,” said Professor Ulf Büntgen from Cambridge’s Department of Geography, the study’s first author.

“We are happy that the knowledge gained in practice about our ibex herds has now been scientifically proven and that ibex hunting in Graubünden can be described as sustainable,” said co-author Hannes Jenny from the Graubünden Hunting and Fishing Authority.

While hunters often select animals based on their age and gender or the quality of the meat and their worthiness as a trophy, the hunting authorities would like to keep the size of individual herds at a level where the surrounding forests can provide them with enough food during the winter. Regardless of these conflicting interests, the most important point from a wildlife biology perspective is that hunting does not negatively affect the wild ibex population in the long term.

̽��ֱ��Alpine ibex is a species that was formerly extinct and is now regarded as a major success story for Swiss conservation. Alpine ibex have a long lifespan (17 years on average) and relatively low reproductive performance, so the Swiss hunt is closely monitored to maintain the animal population. In Graubünden, where around 40% of Switzerland’s ibex live, each hunter may only bring down one female and one male in a particular age group every 10 years. If a hunter violates this requirement, for example by shooting an older animal with longer horns, they have to pay a fine and the animal is confiscated by the authorities.

“Our results also emphasise the importance of continuous monitoring of hunting practices, especially in regions where hunters can choose animals based on certain traits,” said Büntgen.

̽��ֱ��researchers are currently developing a more comprehensive dataset, which will compare the evolutionary pressures on ibex in regions where hunting is allowed against regions where it is prohibited.

Reference:
Ulf Büntgen et al. ‘Horn growth variation and hunting selection of the Alpine ibex.’ Journal of Animal Ecology (2018). DOI: 10.1111/1365-2656.12839

Adapted from a WSL press release.

Researchers studying the hunting of ibex in Switzerland over the past 40 years have shown how hunts, when tightly monitored, can help maintain animal populations at optimal levels.

Our results emphasise the importance of continuous monitoring of hunting practices, especially in regions where hunters can choose animals based on certain traits.

Ulf Büntgen

Reto Barblan, Bergün

Alpine ibex

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Trophy hunting of lions can aid in conservation, but overhaul of system is required, say researchers

sc604 — Fri, 23 Sep 2016 07:00:00 +0000

One year after the worldwide controversy when an American dentist and recreational hunter killed Cecil the Lion outside Hwange National Park in Zimbabwe, the researchers say hunting can work as a conservation tool, but that an overhaul of the system is required in order to encourage hunting companies to prioritise sustainability over profits. Their findings are published in the journal PLOS ONE.

Although it may seem counterintuitive, most lion conservationists agree that trophy hunting can play a key role in conserving the species. Lions need large protected areas to thrive, but managing this land is expensive: in developing countries, the operating budgets for protected areas only cover an average of 30% of costs, and the fees raised from trophy hunting can cover some of this shortfall, making it financially feasible to protect lion habitat instead of developing it for other purposes. However, the researchers say the system is in need of reform if the species is to be protected in the long term.

̽��ֱ��researchers, from the Universities of Kent, Cambridge and Queensland, studied lion population trends between 1996 and 2008 in Tanzania’s Selous Game Reserve. Tanzania is home to up to half of the world’s free-ranging lions and is also the main location for lion trophy hunting in Africa.

̽��ֱ��game reserve, which is a stronghold for the species, is divided into blocks in which hunting rights are allocated to different companies. ̽��ֱ��government leases the land to the hunting companies, enforces hunting regulation and allocates the companies a species-specific annual quota per block.

̽��ֱ��researchers found that in areas where companies were allocated a particular block of land over a short time period (less than ten years), the numbers of lions killed, and the numbers of trophy species killed overall, were higher than the recommended numbers. In addition, annual financial returns were higher for these lands under short-term management.

In contrast, in blocks that were allocated to the same company for ten years or more, the number of offtakes, or licensed lion kills, were at level that were sustainable for the species, while also maintaining their habitat.

“Companies who have secured long-term use rights to natural resources are more likely to manage them sustainably,” said Dr Henry Brink from the ̽��ֱ�� of Kent, the study’s first author. “This is an important lesson for lion conservation, as loss of habitat means this species is increasingly restricted to protected areas.”

This research also supports calls to change the hunting fee system in Tanzania. “At present, the government sells hunting block fees cheaply, and raises more by setting high quotas and high fees for each trophy animal shot, which encourages those who are only allocated blocks over the short-term to shoot more lions, at the expense of long-term sustainability and profits,” said Professor Nigel Leader-Williams from Cambridge’s Department of Geography, the study’s senior author. “Increasing block fees, reducing trophy fees and reducing the hunting quota could bring in the same tax revenue, while reducing the temptation of hunters to kill more lions.”

Reference:
Henry Brink et al. ‘Sustainability and long term-tenure: lion trophy hunting in Tanzania.’ PLOS ONE (2016). DOI: 10.1371/journal.pone.0162610.

Adapted from a ̽��ֱ�� of Kent press release.

New research has found that controlled trophy hunting of lions can actually help conserve the species, but only in areas where hunting companies are given long-term land management rights.

Increasing block fees, reducing trophy fees and reducing the hunting quota could bring in the same tax revenue, while reducing the temptation of hunters to kill more lions.

Nigel Leader-Williams

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Banning trophy hunting could do more harm than good

sc604 — Mon, 11 Jan 2016 06:24:31 +0000

Banning trophy hunting would do more harm than good in African countries that have little money to invest in critical conservation initiatives, argue researchers from the Universities of Cambridge, Adelaide and Helsinki. Trophy hunting can be an important conservation tool, provided it can be done in a controlled manner to benefit biodiversity conservation and local people. Where political and governance structures are adequate, trophy hunting can help address the ongoing loss of species.

̽��ֱ��researchers have developed a list of 12 guidelines that could address some of the concerns about trophy hunting and enhance its contribution to biodiversity conservation. Their paper is published in the journal Trends in Ecology & Evolution.

“ ̽��ֱ��story of Cecil the lion, who was killed by an American dentist in July 2015, shocked people all over the world and reignited debates surrounding trophy hunting,” said Professor Corey Bradshaw of the ̽��ֱ�� of Adelaide, the paper’s senior author.

“Understandably, many people oppose trophy hunting and believe it is contributing to the ongoing loss of species; however, we contend that banning the US$217 million per year industry in Africa could end up being worse for species conservation,” he said.

Professor Bradshaw says trophy hunting brings in more money and can be less disruptive than ecotourism. While the majority of animals hunted in sub-Saharan Africa are more common and less valuable species, the majority of hunting revenue comes from a few valuable species, particularly the charismatic ‘Big Five’: lion, leopard, elephant, buffalo and black or white rhinoceros.

“Conserving biodiversity can be expensive, so generating money is essential for environmental non-government organisations, conservation-minded individuals, government agencies and scientists,” said co-author Dr Enrico Di Minin from the ̽��ֱ�� of Helsinki.

“Financial resources for conservation, particularly in developing countries, are limited,” he said. “As such, consumptive (including trophy hunting) and non-consumptive (ecotourism safaris) uses are both needed to generate funding. Without such these, many natural habitats would otherwise be converted to agricultural or pastoral uses.

“Trophy hunting can also have a smaller carbon and infrastructure footprint than ecotourism, and it generates higher revenue from a lower number of uses.”

However, co-author Professor Nigel Leader-Williams from Cambridge’s Department of Geography said there is a need for the industry to be better regulated.

“There are many concerns about trophy hunting beyond the ethical that currently limit its effectiveness as a conservation tool,” he said. “One of the biggest problems is that the revenue it generates often goes to the private sector and rarely benefits protected-area management and the local communities. However, if this money was better managed, it would provide much needed funds for conservation.”

̽��ֱ��authors’ guidelines to make trophy hunting more effective for conservation are:

Mandatory levies should be imposed on safari operators by governments so that they can be invested directly into trust funds for conservation and management;
Eco-labelling certification schemes could be adopted for trophies coming from areas that contribute to broader biodiversity conservation and respect animal welfare concerns;
Mandatory population viability analyses should be done to ensure that harvests cause no net population declines;
Post-hunt sales of any part of the animals should be banned to avoid illegal wildlife trade;
Priority should be given to fund trophy hunting enterprises run (or leased) by local communities;
Trusts to facilitate equitable benefit sharing within local communities and promote long-term economic sustainability should be created;
Mandatory scientific sampling of hunted animals, including tissue for genetic analyses and teeth for age analysis, should be enforced;
Mandatory 5-year (or more frequent) reviews of all individuals hunted and detailed population management plans should be submitted to government legislators to extend permits;
There should be full disclosure to public of all data collected (including levied amounts);
Independent government observers should be placed randomly and without forewarning on safari hunts as they happen;
Trophies must be confiscated and permits are revoked when illegal practices are disclosed; and
Backup professional shooters and trackers should be present for all hunts to minimise welfare concerns.

Reference:
E. Di Minin et al. ‘Banning Trophy Hunting Will Exacerbate Biodiversity Loss.’ Trends in Ecology & Evolution (2015). DOI: 10.1016/j.tree.2015.12.006

Adapted from a ̽��ֱ�� of Adelaide press release.

Trophy hunting shouldn’t be banned, but instead it should be better regulated to ensure funds generated from permits are invested back into local conservation efforts, according to new research.

There are many concerns about trophy hunting beyond the ethical that currently limit its effectiveness as a conservation tool.

Nigel Leader-Williams

Kevin Pluck

Lion waiting in Namibia

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Lord Byron and the bears beneath Cambridge

amb206 — Wed, 10 Jun 2015 08:00:00 +0000

Scroll to the end of the article to listen to the podcast.

When the eminent architect T G Jackson designed the Sedgwick Museum of Earth Sciences, he added a delightful flourish to the double stairway leading up to the entrance. A pair of brown bears guards one set of steps and a pair of bison the other.

̽��ֱ��choice was apposite. In 1904 geologists found fossilised remains of both bears and bison in the gravels of Barrington, a village south east of Cambridge. Bears and bison were just some of the animals roaming northern Europe 120,000 years ago during an inter-glacial period.

̽��ֱ��Sedgwick Museum takes its name from Adam Sedgwick, one of the founders of modern geology. It’s one of the world’s oldest geological museums and its collection comprises many millions of objects including spectacular ichthyosaurs found by the fossil collector Mary Anning. ̽��ֱ��fossils found in the Barrington Beds by a group of Cambridge geologists are on display in Bay 3. Among the exhibits are remains of hippo, red deer, hyena, bison and elephant – as well as bear and bison.

Look carefully at the stone used to sculpt the animals at the museum entrance and you will see that it’s full of tiny fragments of shells. ̽��ֱ��stone that Jackson chose for the dressings of the building is shelly oolitic limestone of Middle Jurassic age. This stone dates from around 170 million years ago, when marine animals flourished in the warm seas that covered much of the northern hemisphere.

̽��ֱ��bears at the Sedgwick Museum mark the start of a ‘building stones of Cambridge’ walk devised by Dr Nigel Woodcock, Reader in Earth Sciences. He said: “ ̽��ֱ��stone used for the dressings of the Sedgwick Museum come from the Clipsham quarry north west of Stamford. ̽��ֱ��earliest recorded use of Clipsham was for Windsor Castle in the 14th century. Its durability made it a favourite with Victorian architects. In Cambridge, Clipsham was also used for the dressings at Pembroke College, Great St Mary's and King's College Chapel.”

̽��ֱ��Sedgwick Museum is not the only Cambridge building to feature bears: one of several late 16th or early 17th century murals high up inside a tower at Madingley Hall (home to ̽��ֱ�� of Cambridge Institute of Continuing Education) portrays a bear hunt. Until the practise was stopped in the mid-19th century, bears were bred for sport.

One of the figures depicted in the Madingley Hall murals might be a past owner of the hall. Sir Edward Hynde, who was especially fond of hunting, had bread especially baked for the bears he kept in his extensive park.

̽��ֱ��eccentric poet Lord Byron is reported to have kept a bear while he was a student at Trinity College in the early 1800s. He’s said to have purchased the bear, quite possibly at Stourbridge Fair, in defiance of the rules that banned students from keeping dogs in college.

On 26 October 1807 Byron wrote to his friend Elizabeth Pigot: “I have got a new friend, the finest in the world, a tame bear. When I brought him here, they asked me what to do with him, and my reply was, ‘he should sit for a fellowship’.”

Next in the Cambridge Animal Alphabet: C is for an animal that is the source of almost half the meat eaten in the UK, and the bacteria responsible for four out of five cases of food poisoning.

Inset images: Scene showing how some of the plants and mammals found as fossils at Barrington may have looked in life (artwork by Robert Nicholls © 2009 Sedgwick Museum of Earth Sciences, ̽��ֱ�� of Cambridge); 17th century mural at Madingley Hall ( ̽��ֱ�� of Cambridge Institute of Continuing Education).

The Cambridge Animal Alphabet series celebrates Cambridge's connections with animals through literature, art, science and society. Here, B is for Bear – found roaming Cambridgeshire 120,000 years ago, on 17th century murals in Madingley Hall, and keeping Lord Byron company at Trinity College.

I have got a new friend, the finest in the world, a tame bear. When I brought him here, they asked me what to do with him, and my reply was, ‘he should sit for a fellowship’

Lord Byron

Sir Cam

̽��ֱ��Sedgwick Museum bears

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Distance running may be an evolutionary ‘signal’ for desirable male genes

fpjl2 — Wed, 08 Apr 2015 18:05:25 +0000

Pre-birth exposure to high levels of the male sex hormone testosterone has already been shown to confer evolutionary advantages for men: strength of sex drive, sperm count, cardiovascular efficiency and spatial awareness, for example.

Now, latest research on marathon runners using finger length as a marker for hormone exposure shows that people who experienced higher testosterone in the womb are also better at distance running – a correlation particularly strong in men, although also present in women.

Researchers say the finding that males with greater “reproductive potential” from an evolutionary standpoint are better distance runners suggests females may have selected for such athletic endurance when mating during our hunter-gatherer past, perhaps because ‘persistence hunting’ – exhausting prey by tirelessly tracking it – was a vital way to get food.

Distance running may also have acted as a positive ‘signal’ for females of desirable male genetics more generally, say researchers: good runners were likely to be better persistence hunters and consequently better providers. This increases the likelihood they would have other key traits of good providers such as intelligence and generosity.

̽��ֱ��study was conducted by researchers at the ̽��ֱ�� of Cambridge’s Division of Biological Anthropology and is published today in the journal PLOS ONE.

“ ̽��ֱ��observation that endurance running ability is connected to reproductive potential in men suggests that women in our hunter-gatherer past were able to observe running as a signal for a good breeding partner,” said the study’s lead author Dr Danny Longman.

“It was thought that a better hunter would have got more meat, and had a healthier – and larger – family as a consequence of providing more meat for his family. But hunter-gatherers may have used egalitarian systems with equal meat distribution as we see in remaining tribes today. In which case more meat is not a factor, but the ability to get meat would signal underlying traits of athletic endurance, as well as intelligence – to track and outwit prey – and generosity – to contribute to tribal society. All traits you want passed on to your children,” he said.

Using the largest sample of marathon runners of any study of its kind, Longman and colleagues tested for specific finger lengths known as the 2D:4D digit ratio. Previous studies have showed that those exposed to more prenatal testosterone have a longer ring finger (4th digit) in comparison to their index finger (2nd digit).

This digit ratio is the most accurate known way to tell if an adult was exposed to higher levels of testosterone as a foetus – a proven predictor of the “potential for reproductive success” in men, say researchers.

̽��ֱ��team analysed 542 runners (439 men; 103 women) at the Robin Hood half marathon in Nottingham by photocopying hands and taking run times and other key details just after runners crossed the line.

They found that the 10% of men with the most masculine digit ratios were, on average, 24 minutes and 33 seconds faster than the 10% of men with the least masculine digit ratios.

̽��ֱ��correlation was also found in women, but was much more pronounced in men, suggesting a stronger evolutionary selection in men for running ability. ̽��ֱ��10% of women with the most masculine digit ratios were, on average, 11 minutes and 59 seconds faster than the 10% with the least masculine.

Longman points out that prenatal testosterone exposure is a very small influence on running ability that doesn’t compete with training and muscle strength when it comes to performance, but their unprecedentedly large sample size of over 500 people enabled the team to gather conclusive evidence.

“Humans are hopeless sprinters. Rabbits, for example, are much faster sprinters, despite being fat and round. But humans are fantastically efficient long-distance runners, comparable to wolves and wild coyotes,” said Longman.

“We sweat when most animals would overheat; our tendons and posture are designed to propel our next strides – there was likely a selective pressure for all these benefits during our evolution.”

Persistence hunting is thought to have been one of the earliest forms of human hunting, evolving approximately two million years ago, said Longman.

“You can still see examples of persistence hunting in parts of Africa and Mexico today. Hunters will deliberately choose the hottest time of day to hunt, and chase and track an antelope or gnu over 30 to 40 kilometres for four or five hours. ̽��ֱ��animal recovers less and less from its running until it collapses exhausted and is easy to kill,” Longman said.

“This may sound crazy, but when a hunter is relatively fit the amount of energy they expend is actually tiny compared to the energy benefits of an antelope-sized animal, for example. Before the domestication of dogs, persistence hunting may have been one of the most efficient forms of hunting, and as a consequence may have shaped human evolution.”

New research shows that males with higher ‘reproductive potential’ are better distance runners. This may have been used by females as a reliable signal of high male genetic quality during our hunter-gatherer past, as good runners are more likely to have other traits of good hunters and providers, such as intelligence and generosity.

Persistence hunting may have been one of the most efficient forms of hunting, and as a consequence may have shaped human evolution

Danny Longman

Warein

Running

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Colour-morphing reef fish is a 'wolf in sheep's clothing'

fpjl2 — Thu, 19 Mar 2015 15:45:31 +0000

A new study has shown that the dottyback, a small predatory reef fish, can change the colour of its body to imitate a variety of other reef fish species, allowing the dottyback to sneak up undetected and eat their young.

̽��ֱ��dottyback also uses its colour-changing abilities to hide from larger predators by colour-matching to the background of its habitat - disappearing into the scenery.

̽��ֱ��research, published today in the journal Current Biology, reveals a sophisticated new example of 'mimicry': disguising as a different species to gain evolutionary advantage.

While using mimicry to hunt or hide from other species is commonplace in nature - from cuckoos to butterflies - scientists point out that if the same physical deception is encountered too frequently, species on the receiving end become more vigilant and develop tactics to mitigate the mimics.

̽��ֱ��dottyback, however, is able to colour-morph depending on the particular colour of the surrounding species it is currently hunting: different types of damselfish being a popular target.

Scientists say that this flexibility of physical mimicry makes it much harder for the dottyback's prey to develop detection strategies and avoid getting eaten.

"By changing colour to imitate local damselfish communities, dottybacks are able to overcome the predator avoidance behaviour in the juvenile fish they hunt," said Dr William Feeney, co-author of the study from the ̽��ֱ�� of Cambridge's Department of Zoology.

" ̽��ֱ��dottyback behaviour is comparable to the 'wolf in sheep's clothing' scenario from Aesop's Fables, where distinguishing the predator from the harmless 'flock' becomes increasingly difficult when they look alike - allowing the dottyback to creep up on unsuspecting juvenile damselfish," Feeney said.

Dottybacks are generally solitary and highly territorial predators of around eight centimetres in length, commonly found in Indo-Pacific coral reefs.

While dottybacks can vary their colouration from pink to grey, the researchers focused on two colour 'morphs' - yellow and brown - that both occur on the reefs surrounding Lizard Island, off the coast of north-east Australia. This is because the area has populations of both yellow and brown damselfish, and habitat consisting of live coral and dead coral 'rubble'.

̽��ֱ��scientists built their own simulated reef outcrops comprising both live coral and rubble, and stocked them with either yellow or brown damselfish. When released into reefs with damselfish of the opposite colour, scientists found the dottybacks would change from yellow to brown or vice versa over the course of approximately two weeks.

Anatomical study of dottyback skin cells revealed that while the level of 'chromatophores' - pigment-containing cells that reflect light - remain constant, the ratio of yellow pigment cells to black pigment cells shifts to move the dottyback from yellow to brown or back again.

̽��ֱ��team conducted lab experiments with adult and juvenile damselfish to test whether this colour change affects dottyback hunting success. They found that once the dottyback matched the colour of the damselfish, they were up to three times more successful at capturing juvenile damselfish.

̽��ֱ��scientists also found that the dottyback use their colour-morphing powers to blend into the coral of their habitats to hide from their own predators, such as the coral trout - a predator they share with damselfish, who have also adapted to match the colour of their environment.

̽��ֱ��scientists measured the strike rates of coral trout when exposed to images of different colours of dottyback against different habitats. ̽��ֱ��coral trout had trouble picking out the fish when the colour matched the habitat.

"While the dottybacks change colour to aggressively mimic damselfish, they may also gain a secondary benefit: a reduced risk of being eaten themselves. Damselfish have evolved to blend into their environment, so, by imitating the damselfish, they also colour-match the habitat - making it harder for coral trout to see them," said Feeney.

"This is the first time that an animal has been found to be able to morph between different guises in order to deceive different species, making the dottyback a pretty crafty little fish"

Inset image: dottyback eyeing up damselfish prey, credit Christopher E Mirbach

̽��ֱ��dottyback changes its colour to match surrounding damselfish species, enabling it to counter the defences of its damselfish prey by disguising itself as a harmless part of their community, then swoop in to hunt their young.

This is the first time that an animal has been found to be able to morph between different guises in order to deceive different species, making the dottyback a pretty crafty little fish

William Feeney

Justin Marshall

Brown Vs Yellow Dottyback

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