Honey, We Shrunk the Cod
Experts have suspected that commercial fishing might be to blame. For years, the cod were intensely harvested, caught in enormous trawl nets. The smallest cod could wriggle their way out of danger, while the biggest, heaviest specimens were continually removed from the sea.
One simple explanation for the phenomenon, then, was that the fish were not actually shrinking: Rather, they were simply eliminated as soon as they grew big enough to be caught.
But a new study suggests that intense fishing was driving the evolution of the fish. Small, slow-growing cod gained a significant survival advantage, shifting the population toward fish that were genetically predisposed to remaining small. Today's cod are small not because the big individuals are fished out but because the fish no longer grow big.
The data, which were published on Wednesday in the journal Science Advances, add to a growing body of evidence that human activities like hunting and fishing are driving the evolution of wild animals — sometimes at lightning speed.
'Human harvesting elicits the strongest selection pressures in nature,' said Thorsten Reusch, a marine ecologist at the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany and an author of the new paper. 'It can be really fast that you see evolutionary change.'
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Medscape
28 minutes ago
- Medscape
Is Red Meat Bad for You? The Proof Is in the Processing
This transcript has been edited for clarity. Is red meat bad for you? On the one hand, meat makes you strong, and it's every American's God-given right to grill a steak on his barbecue during the summer. I believe this came up in a church synod at some point… But on the other hand, the WHO (World Health Organization) has declared red meat a carcinogen, with a hot dog being as bad as cigarette. Yes, that was headline when the report came out. So, how do we reconcile these opposing ideas? Part of the solution is realizing the WHO organization in question is based in France. Maybe they're still angry about the "freedom fries" thing, but actually examining the nuances of the French language will help us understand what's going on. If you don't speak French, don't worry I got you covered. Ce n'est pas si difficile de tout n'inquiétez vous pas. Vous allez voir . Sit back, grab a baguette, and let's find out how dangerous red meat really is. I'm Christopher Labos, and this is Medscape's On Second Thought . Bonjour, tout le monde! Now, meat doesn't seem like it should be a complex topic to study, but it is. Many people around the world eat animals, but we don't all eat the same animals. For example, this is a cow, often used to make hamburger and steak. And this is Tobi, God's perfect angel who gets a more elaborate birthday party than I do each year. He is my son, and I would throw myself in front of a moving car for him. By necessity, when we do medical research on meat, we are lumping together a whole lot of a different human behavior, with people eating different types of animals based on where they live. There's no real alternative, and frankly, you can't let the perfect become the enemy of the good. Most credible research will at least separate out red meat from white meat. But most people don't really know what the difference is. If you thought pork was white meat, you're wrong. You think that because of a marketing slogan. In 1987, the National Pork Board paid for the marketing campaign "Pork. The Other White Meat." They were basically trying to position pork as an alternative to chicken. People also usually think veal or deer is white meat. They think the difference between white and red meat has something to do the age of the animal, whether its free range, or the color of the meat. But it doesn't. Chefs and restaurants say all kinds of things, but the real definition is simple: Mammals are red meat, and birds are white meat. Now, there's another thing we need to explain. We have red meat, but we also have processed red meat. Processed red meat is when red meat is transformed in some way — and that doesn't mean cooking. If you just take a piece of steak and cook it on your barbecue or in the oven, that's not processed meat. Processing is doing things like salting the meat, smoking it, or curing it. Processed meat includes items like bacon, sausages, hot dogs, salami, corn beef, and smoked meat. So, when we talk about red meat and health risks, we are primarily talking about processed red meat. And the people talking about this are the International Agency for Research in Cancer (IARC). IARC is a WHO organization, and their mandate is to promote international research on cancer — particularly its cause. One of their programs is a monograph program that evaluates the evidence of the carcinogenicity of specific exposures. Here's where a knowledge of French is going to come in handy. IARC likes to look at something called the hazard, rather than the risk. In fact, every time they have a press conference, they spend about 5 minutes explaining the difference to people, which begs the question: Why not just study risk and be done with it? In English, those words seem pretty much like synonyms. And with the way most people use them, they essentially are. But in French, they are slightly different. Le risque et le hasard don't quite mean the same thing in French. To be fair, their definitions are technically different in English, as well — as those of you who read the dictionary for fun already know. A risk is the probability that something harmful will happen. A hazard is a potential source of harm. For example, a grenade is a hazardous thing to have on your desk, but the risk of it exploding is quite low… unless you pull the pin. IARC is researching hazard. They are evaluating whether something is associated with cancer, not how risky that something is. IARC categorizes everything into groups: carcinogenic to humans, probably carcinogenic, possibly carcinogenic, or not classifiable. There is technically a "not carcinogenic" group, but there's nothing in there. Well, there was one substance in there for a bit, but they removed it. Comment below if you know what that substance is. Here's a hint: You find it in yoga pants. So, IARC has never found anything that doesn't cause cancer. When they go hunting for heffalumps and woozles, they find heffalumps and woozles. To be fair, which I am under no contractual obligation to be, they are a WHO agency, and they are tasked to review substances that are of interest to world governments. As such, they are not going to review stuff that is clearly unrelated to cancer… but still. They put a lot of stuff in Group 1, the (definitely) carcinogenic group. Tamoxifen is in Group 1, and as most of you know, tamoxifen treats breast cancer. It has saved countless lives. Calling it a carcinogen sounds a bit daft, but it is associated with abnormal uterine bleeding and an increased risk of uterine cancer. And the data is pretty uncontroversial, right? Thus, IARC says, 'We are certain this association is true, therefore it goes in Group 1.' But what's the risk of tamoxifen causing uterine cancer? It's 0.3% on the absolute risk scale. It's basically zero and a heck of a lot lower than the breast cancer risk. Clearly, you should take the drug if you have ER-positive breast cancer. So, this is the problem. IARC is saying how certain they are that something is dangerous, but not how dangerous something is. Conclusive data will land a substance into Group 1: carcinogenic. Strong but not conclusive data goes into Group 2a: probably carcinogenic. If there's only some evidence, contradictory evidence, or maybe just animal data, you get sorted into Group 2b: possibly carcinogenic. And Group 3 is used when there's not much data to work off of. Generally, their system works okay. They put tobacco, asbestos, and gamma radiation in Group 1, which makes sense. But then also put stuff like birth control pills, estrogen, and tamoxifen in Group 1. Sure, there is a small increased risk of breast cancer with birth control pills if you have a family history, but it's a pretty small risk and frankly negligible for the general population — plus, it's largely outweighed by the decrease in ovarian cancer risk that comes with using birth control pills. But IARC isn't doing that type of nuanced calculation. They say, 'Estrogen causes breast cancer. The pill has estrogen. The link is proven. The pill goes into Group 1.' So, it was IARC that reviewed all the data about processed red meat and declared it a Group 1 carcinogen. Fun fact: Unprocessed red meat was only put in Group 2A because the data was less solid. For anybody grilling a steak right now, this doesn't apply to you. But not everybody agreed with IARC. The Nutritional Recommendations (NutriRECS) Consortium was a group of researchers who also reviewed the data on red meat and came to a completely different conclusion. Their analysis was motivated by two things: 1) the funding they received from the beef industry (this is why we can't have nice things), and 2) they dismissed much of the research because it comes from observational cohorts, not randomized controlled trials. In food science, randomized controlled trials are hard to conduct, because telling people what to eat is often met with "make me." Regardless, the NutriRECS Consortium conclusion was, 'Keep eating meat, as the data is uncertain because most of it is observational.' This conclusion is a bit reductionist to me, because we have a lot of observational data pointing toward health risks associated with processed red meat, and I have a hard time believing all the stuff added to processed red meat is doing us any favors. But let's take the IARC assessment at face value. They are convinced by the hazard or the hasard. But what's the risk? The cancer risk is most clear cut for colon cancer, which is pretty logical. Your lifetime risk of colon cancer is about 4%, assuming you're of general risk with no family history or genetic risk factors. It's actually 4.2% for males and 4.0% for females, according to the 2022 Cancer Statistics from the American Cancer Society. But let's say 4% for everyone — just for simplicity. The IARC report estimated that eating an extra 50 g of processed meat per day, every day, increased your risk of colorectal cancer by 18%. Take 4%, multiply it by 1.18, and you get 4.72%. So, let's say 5% if we're rounding. All this to say, if you eat hot dogs every day of your life, your risk of getting colon cancer goes up by 1 percentage point on the absolute scale. Now, on first instinct you might say, "Pfff, that's nothing. Pass the bratwurst." But 1% on the absolute scale is not trivial. That's thousands of cases per year. Millions of cases over the course of your lifetime in a country of 300 million people. It has some important public health implications. Is the risk high enough for us to stop killing and eating Bambi's mother? Hard to say. It's not negligible, but it's not astronomical either. And there are economic and environmental factors to keep in mind — issues that are often forgotten when we talk about medicine. I will stress one point, though. The IARC estimates of 1% absolute risk increase are about daily consumption of processed meat. You don't need to eat jerky every day of your life. For Medscape, I'm Dr Christopher Labos… with Tobi.
Yahoo
5 hours ago
- Yahoo
2.6 million-year-old stone tools reveal ancient human relatives were 'forward planning' 600,000 years earlier than thought
When you buy through links on our articles, Future and its syndication partners may earn a commission. Ancient human relatives moved diverse stones over substantial distances, researchers report, revealing a surprisingly high degree of forward planning 600,000 years earlier than experts previously thought possible. In a study published Friday (Aug. 15) in the journal Science Advances, a team of researchers pored over 401 stone tools from the archaeological site of Nyayanga in Kenya, dated to 3 million to 2.6 million years ago. The tools were made in the earliest known style called Oldowan, which involved chipping flakes off one stone using another stone to make a basic tool. But the kinds of rocks used were surprising — most of them came from locations over 6 miles (9.7 kilometers) away. Chimpanzees (Pan troglodytes) are also known to carry granite hammerstones for cracking nuts as far as 1.2 miles (2 km), but only through cumulative, shorter-distance bouts, previous research has shown. The new finding establishes that human relatives could move tools more substantial distances, suggesting a better ability to plan ahead. "People often focus on the tools themselves, but the real innovation of the Oldowan may actually be the transport of resources from one place to another," study co-author Rick Potts, a paleoanthropologist at the National Museum of Natural History in Washington, D.C., said in a statement. "The knowledge and intent to bring stone material to rich food sources was apparently an integral part of toolmaking behavior at the outset of the Oldowan." The oldest stone tools date back about 3.3 million years, nearly 1 million years before experts think our genus, Homo, originated. These tools were probably created by human ancestors like the australopithecine Lucy. But these early tools were made out of materials sourced locally or from a short distance — roughly 1.7 miles (3 kilometers) away at the most. Around 2 million years ago, human ancestors such as Homo erectus went through some big changes: There were increases to their brain size and body size, some migrated out of Africa, and some began cooking and eating meat. There is also evidence that these early ancestors began to plan ahead, becoming more selective about the rocks they chose to make into tools, and procuring them from significant distances. But the stone tools from Nyayanga are 600,000 years older than the earliest evidence that human relatives were selecting and transporting rocks long-distance, and also likely predates the emergence of the Homo genus. This means that these groups were figuring out what they needed to process food and how to mentally map their environment, according to Potts. Related: 1.5 million-year-old stone tools from mystery human relative discovered in Indonesia — they reached the region before our species even existed It is not clear, however, which species made the tools discovered at Nyayanga. "Unless you find a hominin fossil actually holding a tool, you won't be able to say definitively which species are making which stone tool assemblages," study co-author Emma Finestone, a biological anthropologist at the Cleveland Museum of Natural History, said in the statement. In this case, the tools were found alongside some fossils attributed to the genus Paranthropus, which "calls into question whether the transport of core and flake technology was exclusive to genus Homo," the researchers wrote in the study. RELATED STORIES —1.5 million-year-old bone tools crafted by human ancestors in Tanzania are oldest of their kind —Massive, 1.2 million-year-old tool workshop in Ethiopia made by 'clever' group of unknown human relatives —Our ancestor Lucy may have used tools more than 3 million years ago Regardless of which species of human relative produced the tools, the fact that they transported them long distances suggests they were far more intelligent than they have been given credit for. "Humans have always relied on tools to solve adaptive challenges," Finestone said in the statement. "By understanding how this relationship began, we can better see our connection to it today — especially as we face new challenges in a world shaped by technology." Human evolution quiz: What do you know about Homo sapiens? Solve the daily Crossword
Yahoo
7 hours ago
- Yahoo
Calls for ‘landscape-wide' action to protect butterflies amid falling numbers
Conservationists have called for 'landscape-wide' action to protect butterflies, as new official figures indicate declines of nearly a fifth since the 1970s. The latest annual update on butterfly monitoring published by the Environment Department (Defra) reveal abundance across all butterfly species has declined 18% in the UK and 19% in England over the long-term. The situation is even worse for specialists which need specific habitats such as flower-rich grassland, heathland and woodland clearings to thrive, with numbers declining by more than a third (39%) across the UK, and 25% in England. And some individual species of butterflies have seen numbers plummet by more than 80% since 1976, the monitoring suggests. Conservationists warn falls in the abundance of butterflies are a signal of problems in the wider environment, and reveal what is happening to many other insects that are a key part of ecosystems. The latest figures include 2024, which wildlife charity Butterfly Conservation's head of science Dr Richard Fox described as a 'terrible year for the UK's butterflies'. May last year was the warmest on record, but had notably low levels of sunshine, and overall 2024 ranked as the fourth warmest and eighth wettest year since the early 1900s, disrupting seasonal patterns essential to many butterfly species. The weather conditions hit butterflies which were already struggling with habitat loss and pollution, conservationists warn. Dr Fox said: 'With the addition of data from 2024, which was a terrible year for the UK's butterflies, these updated indicators reiterate the long-term decline of these beautiful insects. 'In particular, habitat specialists – butterfly species that rely on specific habitats such as heathland, woodland clearings or flower-rich grassland – have fared poorly since the 1970s as humans have destroyed and polluted these habitats. 'When we also factor in the implications of climate change, which is resulting in unpredictable extremes of weather, it is more important than ever that we take conservation action on a landscape-wide scale.' The data indicate nearly half (46%) of individual species that are restricted to certain habitats have seen declines in the UK, while 50% have seen numbers fall in England. Across the UK, heath fritillary has seen the most severe declines since 1976 with an 89% drop in abundance, while other habitat specialists including wood white, small-bordered fritillary, grayling and pearl-bordered fritillary have seen declines of 70% to 80%. The assessment from Defra said the main causes for the declines in habitat specialist butterflies were the loss, fragmentation and degradation of those landscapes, with more intensive agriculture also contributing to the drop in numbers. Many have not recovered from declines experienced in the late 1970s, which were partly as a result of the knock-on effects of the drought conditions in 1976, but a lack of suitable habitat after that is the main driver for persistent declines and lack of recovery since, it said. Butterflies found on farmland have declined by around a third in both the UK and England, with those that require the specific habitat to thrive seeing falls in abundance of 42% in the UK and 47% in England. Woodland butterflies have fared even worse with declines of more than half (54%) since the 1970s when monitoring began, with woodland specialist species declining by 55% in the UK and 57% in England. Butterflies have also seen short-term declines on farmland, with numbers falling 12% across the UK and 11% in England over the past decade, the figures suggest, while woodland butterflies have shown no significant change over the same period. But the findings also indicate some specialist species are on the increase, including black hairstreak, silver-spotted skippers, large heath, dark green fritillary, silver-washed fritillary and purple emperor. Officials said some recent increases could be attributed to targeted conservation action, while some species are benefiting from climate change which is allowing them to expand their range. Dr Fox urged: 'Looking at the specific conditions these species need to thrive and working to reinstate them where we can will offer some of these very vulnerable species an opportunity to recover.' Across more 'generalist' species, which are not restricted to specific habitats, there has been no change over the long or short-term, but the fortunes of individual species have differed wildly. Small tortoiseshell butterflies have seen falls of 86% between 1976 and 2024, while wall and white-letter hairstreak butterflies have seen almost as severe declines. But ringlet butterflies have increased by 273%, and holly blue and comma butterflies have also seen some of the largest increases in abundance over five decades, the figures suggest. Across the 50 species monitored across the UK, 44% have suffered declines since 1976, while 47% of the 49 species assessed in England have seen drops since then. Some 28% of individual species have increased across the UK and 24% have increased in England, the statistics indicate.
