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Helping immigrants helps their kids
IN BRIEF
KONRAD WOTHE / LOOK-FOTO / GETTY
WHAT is the point of the enormous leaves found on tropical plants? It may be to do with maintaining a comfortable temperature. Large-leaved plants like bananas tend to live in the tropics, while small-leaved plants like heather are closer to the poles. Botanists first noticed this trend in the 19th century but no one has been able to explain it. Large leaves absorb more of the sun’s heat and get hotter than small ones, so if overheating is the issue, big leaves should be found in cold regions, not the tropics. To solve the puzzle, Ian Wright at Macquarie University in Sydney and his colleagues studied 7670 plant species from different latitudes. They looked at the relationship between leaf size and aspects of climate such as day and night temperatures, rainfall and humidity. They found that it was just as important to avoid night-time freezing as daytime heat stress (Science, doi.org/ccpm). Large leaves have thick layers of still air around them, which makes it harder to extract heat from the surroundings at night. This makes them a bad idea in high latitudes. They are also bad in hot deserts because they overheat in the day. But big leaves do well in hot, wet, tropical climates because they can cool down using transpiration – the plant version of sweating.
20 | NewScientist | 9 September 2017
Europa plume may not exist, making hunt for life harder JUPITER’S icy moon Europa may be one of the most promising places to look for alien microbes, thanks to its subsurface ocean. Plumes of water thought to be spewed into space from the ocean would make the search easier – but now it seems these plumes could just be warm rocks. NASA’s Galileo probe, which orbited Jupiter between 1995 and 2003, observed a “hotspot” in the Pwyll crater – normally indicative of an underground heat source that could fuel a spout of water. But although researchers
suspected the heat source may be a plume, the results were never confirmed. Now Samantha Trumbo and Mike Brown at the California Institute of Technology have compared daytime observations of the anomalous spot with previous night-time ones made by Galileo (arxiv.org/abs/1708.07922). “Our data are not consistent with a current subsurface heat source,” says Trumbo. “That doesn’t necessarily mean there’s no plume there.” Key to the mystery is the way
different rocks retain heat. For example, sand heats up quickly during the day and cools fast at night, while pebbles or boulders take a while to heat up, but retain that warmth well into the night. This slower kind of retention may be at work in the Pwyll crater. Testing the liquid that is strongly suspected to lie beneath Europa’s icy crust would be easier if it was being shot out into space, where a spacecraft could collect samples. The alternative would involve the tricky feat of finding a way to drill through the thick ice. ALBIN LOHR-JONES/PACIFIC PRESS/LIGHTROCKET VIA GETTY IMAGES
Why some plants have huge leaves
For new stories every day, visit newscientist.com/news
Sneaky beetles steal ants’ food NEVER trust a beetle, if you’re an ant. They might take your food. When jet ants go foraging they use marked trails to transport the honeydew they collect from aphids in special stomachs called “crops”. But sap beetles (Amphotis marginata) lurk on these paths and dupe food-laden ants into regurgitating meals for them. Now, Bert Hölldobler and Christina Kwapich at Arizona State University in Tempe have found that the beetles get most of their food this way. “Ants feed each other honeydew collected in their crops by essentially vomiting into each other’s mouths,” says Kwapich. “The beetles have capitalised on this behaviour.” To do this, a beetle approaches an ant and taps on it with its front legs and antennae. Then the beetle presses its own mouthparts on those of the ant, encouraging it to regurgitate a big drop of food. Hölldobler and Kwapich fed ants radioactive honey water. They found that beetles placed among fed ants obtained 1.8 times as much food as other ants did from their own kind (PLoS One, doi.org/gbq2pz). The relationship was strictly one-way.
Helping immigrants helps their kids A SCHEME that protects immigrants from deportation has also benefited the mental health of their children. The Deferred Action for Childhood Arrivals (DACA) programme was introduced in the US in 2012. It provides work permits and protection from deportation to undocumented immigrants who arrived in the US as children before 2007. To assess the mental health of families in these situations, Jens Hainmueller at Stanford University in California and his team have analysed data from Oregon’s Emergency Medicaid programme. They focused
on 5600 immigrant mothers who used the scheme between 2003 and 2015, and their 8610 children. When mothers weren’t eligible for DACA protection, 7.8 per cent of their children were diagnosed with adjustment or anxiety disorders. When mothers were eligible, the figure was only 3.3 per cent (Science, doi.org/ccn4). “The fact that it reduced by over 50 per cent is really astonishing,” says Sarah Lowe at Montclair State University in New Jersey. “It shows that this policy can have huge impacts on the life of an entire family.”
KONRAD WOTHE / LOOK-FOTO / GETTY
WHAT is the point of the enormous leaves found on tropical plants? It may be to do with maintaining a comfortable temperature. Large-leaved plants like bananas tend to live in the tropics, while small-leaved plants like heather are closer to the poles. Botanists first noticed this trend in the 19th century but no one has been able to explain it. Large leaves absorb more of the sun’s heat and get hotter than small ones, so if overheating is the issue, big leaves should be found in cold regions, not the tropics. To solve the puzzle, Ian Wright at Macquarie University in Sydney and his colleagues studied 7670 plant species from different latitudes. They looked at the relationship between leaf size and aspects of climate such as day and night temperatures, rainfall and humidity. They found that it was just as important to avoid night-time freezing as daytime heat stress (Science, doi.org/ccpm). Large leaves have thick layers of still air around them, which makes it harder to extract heat from the surroundings at night. This makes them a bad idea in high latitudes. They are also bad in hot deserts because they overheat in the day. But big leaves do well in hot, wet, tropical climates because they can cool down using transpiration – the plant version of sweating.
20 | NewScientist | 9 September 2017
Europa plume may not exist, making hunt for life harder JUPITER’S icy moon Europa may be one of the most promising places to look for alien microbes, thanks to its subsurface ocean. Plumes of water thought to be spewed into space from the ocean would make the search easier – but now it seems these plumes could just be warm rocks. NASA’s Galileo probe, which orbited Jupiter between 1995 and 2003, observed a “hotspot” in the Pwyll crater – normally indicative of an underground heat source that could fuel a spout of water. But although researchers
suspected the heat source may be a plume, the results were never confirmed. Now Samantha Trumbo and Mike Brown at the California Institute of Technology have compared daytime observations of the anomalous spot with previous night-time ones made by Galileo (arxiv.org/abs/1708.07922). “Our data are not consistent with a current subsurface heat source,” says Trumbo. “That doesn’t necessarily mean there’s no plume there.” Key to the mystery is the way
different rocks retain heat. For example, sand heats up quickly during the day and cools fast at night, while pebbles or boulders take a while to heat up, but retain that warmth well into the night. This slower kind of retention may be at work in the Pwyll crater. Testing the liquid that is strongly suspected to lie beneath Europa’s icy crust would be easier if it was being shot out into space, where a spacecraft could collect samples. The alternative would involve the tricky feat of finding a way to drill through the thick ice. ALBIN LOHR-JONES/PACIFIC PRESS/LIGHTROCKET VIA GETTY IMAGES
Why some plants have huge leaves
For new stories every day, visit newscientist.com/news
Sneaky beetles steal ants’ food NEVER trust a beetle, if you’re an ant. They might take your food. When jet ants go foraging they use marked trails to transport the honeydew they collect from aphids in special stomachs called “crops”. But sap beetles (Amphotis marginata) lurk on these paths and dupe food-laden ants into regurgitating meals for them. Now, Bert Hölldobler and Christina Kwapich at Arizona State University in Tempe have found that the beetles get most of their food this way. “Ants feed each other honeydew collected in their crops by essentially vomiting into each other’s mouths,” says Kwapich. “The beetles have capitalised on this behaviour.” To do this, a beetle approaches an ant and taps on it with its front legs and antennae. Then the beetle presses its own mouthparts on those of the ant, encouraging it to regurgitate a big drop of food. Hölldobler and Kwapich fed ants radioactive honey water. They found that beetles placed among fed ants obtained 1.8 times as much food as other ants did from their own kind (PLoS One, doi.org/gbq2pz). The relationship was strictly one-way.
Helping immigrants helps their kids A SCHEME that protects immigrants from deportation has also benefited the mental health of their children. The Deferred Action for Childhood Arrivals (DACA) programme was introduced in the US in 2012. It provides work permits and protection from deportation to undocumented immigrants who arrived in the US as children before 2007. To assess the mental health of families in these situations, Jens Hainmueller at Stanford University in California and his team have analysed data from Oregon’s Emergency Medicaid programme. They focused
on 5600 immigrant mothers who used the scheme between 2003 and 2015, and their 8610 children. When mothers weren’t eligible for DACA protection, 7.8 per cent of their children were diagnosed with adjustment or anxiety disorders. When mothers were eligible, the figure was only 3.3 per cent (Science, doi.org/ccn4). “The fact that it reduced by over 50 per cent is really astonishing,” says Sarah Lowe at Montclair State University in New Jersey. “It shows that this policy can have huge impacts on the life of an entire family.”