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Toxic waters turn sea snakes black
GARY BELL/SEAPICS.COM
NEWS & TECHNOLOGY
Toxic waters turn sea snakes black Aylin Woodward
POLLUTION from mining activities may be encouraging some sea snakes to evolve black skins – the first evidence of “industrial melanism” in a marine species. Industrial melanism has been seen in invertebrate species, most famously the peppered moth. During Britain’s Industrial Revolution, the frequency of darkcoloured versions of this moth skyrocketed. Schoolchildren are often taught that such insects blended in with the soot-covered bark of trees in industrial areas, so their odds of surviving and breeding rose – although this might be an oversimplification. In vertebrates, industrial melanism is vanishingly rare, says Rick Shine at the University of Sydney, but the Indo-Pacific sea snakes he and his colleagues study may provide a good example. The turtle-headed sea snake (Emydocephalus annulatus) is largely found in certain tropical waters near Australia. Usually, the snakes look like black-and-white banded candy canes. But Shine and his colleagues found that
Polite robots learn to keep out of our way FOR robots to coexist amicably with us, they need to learn about personal space. A software upgrade could help droids navigate crowded places like malls without jostling people around them. Harmish Khambhaita and Rachid Alami at the University of Toulouse in France wanted to programme a robot to mimic human manners like 10 | NewScientist | 19 August 2017
individuals living near polluted areas on the island of New Caledonia, a French overseas territory north-east of Brisbane, are entirely black. The group already knew that pollutants such as arsenic or lead can bind to melanin, a dark pigment in the skin, and they wondered whether this might explain the black snakes. To find out, they collected and analysed the skins naturally shed – or “sloughed” – by the snakes. Studying 17 turtle-headed sea snake sloughs, the group found that the concentrations of 13 trace elements – particularly cobalt, manganese, lead, zinc and nickel – were higher in snakes near urban areas, and higher in darker skin. Shine says similar concentrations of those trace elements have been reported to cause severe health problems in many domesticated species, from cattle to poultry. What is more, Shine’s group found that the black sea snakes shed their skins twice as often as their lighter counterparts. This suggests the snakes are, indeed, adapting to deal with the polluted water – both by developing skin with a better capacity to bind
stepping around one another, yielding to groups and respecting personal space. “The robot has to reason what the human would like to do and react,” says Khambhaita. This may seem akin to what driverless cars do, but humans are tougher to predict than traffic. “We know where the roads are going and what the crossing points are,” he says. “Indoors, the paths are not predefined. Anybody can move anywhere.” In order to apply its etiquette lessons, the bot first needed a navigation upgrade. Robots normally
–Changed its stripes–
potentially harmful trace elements, and by shedding that skin more often to reduce their trace element load (Current Biology, doi.org/cbrc). The shallow waters, particularly near the New Caledonian city of Nouméa, are highly polluted by intensive mining activity and industrialisation. “Our urban, turtle-head sites are literally right beside the city
of Nouméa,” says Shine. The city also has a large nickel factory. The study does seem to suggest the sea snakes are evolving in response to industrial pollutants, says Susana Clusella-Trullas at Stellenbosch University in South Africa. But she wants to know whether black sea snakes have higher survival rates and more offspring than their paler peers in these polluted environments. n
get around using a two-step process, with the robot trying to predict where other objects will be, then planning how to move. If something moves unexpectedly between the steps, the software can freeze up. To fix this, the team wrote new software combining the steps, so the robot constantly adjusts its planned path (arxiv.org/abs/1708.01267). Two laser scanners let their robot detect
objects such as furniture, and a motion capture system tracked human positions using markers stitched into helmets that volunteers wore. Every tenth of a second the robot scanned for changes, then updated its predictions and trajectory, all while remaining fastidiously polite. The team tested their robot in a 15-by-20-metre hallway with rooms on both sides. It was able to avoid bumping into people when someone was walking towards it, and when two people were passing on either side. It also yielded to a person emerging from a doorway. Aylin Woodward n
“The robot mimics our manners – it has to reason what a human would like to do, and react”
NEWS & TECHNOLOGY
Toxic waters turn sea snakes black Aylin Woodward
POLLUTION from mining activities may be encouraging some sea snakes to evolve black skins – the first evidence of “industrial melanism” in a marine species. Industrial melanism has been seen in invertebrate species, most famously the peppered moth. During Britain’s Industrial Revolution, the frequency of darkcoloured versions of this moth skyrocketed. Schoolchildren are often taught that such insects blended in with the soot-covered bark of trees in industrial areas, so their odds of surviving and breeding rose – although this might be an oversimplification. In vertebrates, industrial melanism is vanishingly rare, says Rick Shine at the University of Sydney, but the Indo-Pacific sea snakes he and his colleagues study may provide a good example. The turtle-headed sea snake (Emydocephalus annulatus) is largely found in certain tropical waters near Australia. Usually, the snakes look like black-and-white banded candy canes. But Shine and his colleagues found that
Polite robots learn to keep out of our way FOR robots to coexist amicably with us, they need to learn about personal space. A software upgrade could help droids navigate crowded places like malls without jostling people around them. Harmish Khambhaita and Rachid Alami at the University of Toulouse in France wanted to programme a robot to mimic human manners like 10 | NewScientist | 19 August 2017
individuals living near polluted areas on the island of New Caledonia, a French overseas territory north-east of Brisbane, are entirely black. The group already knew that pollutants such as arsenic or lead can bind to melanin, a dark pigment in the skin, and they wondered whether this might explain the black snakes. To find out, they collected and analysed the skins naturally shed – or “sloughed” – by the snakes. Studying 17 turtle-headed sea snake sloughs, the group found that the concentrations of 13 trace elements – particularly cobalt, manganese, lead, zinc and nickel – were higher in snakes near urban areas, and higher in darker skin. Shine says similar concentrations of those trace elements have been reported to cause severe health problems in many domesticated species, from cattle to poultry. What is more, Shine’s group found that the black sea snakes shed their skins twice as often as their lighter counterparts. This suggests the snakes are, indeed, adapting to deal with the polluted water – both by developing skin with a better capacity to bind
stepping around one another, yielding to groups and respecting personal space. “The robot has to reason what the human would like to do and react,” says Khambhaita. This may seem akin to what driverless cars do, but humans are tougher to predict than traffic. “We know where the roads are going and what the crossing points are,” he says. “Indoors, the paths are not predefined. Anybody can move anywhere.” In order to apply its etiquette lessons, the bot first needed a navigation upgrade. Robots normally
–Changed its stripes–
potentially harmful trace elements, and by shedding that skin more often to reduce their trace element load (Current Biology, doi.org/cbrc). The shallow waters, particularly near the New Caledonian city of Nouméa, are highly polluted by intensive mining activity and industrialisation. “Our urban, turtle-head sites are literally right beside the city
of Nouméa,” says Shine. The city also has a large nickel factory. The study does seem to suggest the sea snakes are evolving in response to industrial pollutants, says Susana Clusella-Trullas at Stellenbosch University in South Africa. But she wants to know whether black sea snakes have higher survival rates and more offspring than their paler peers in these polluted environments. n
get around using a two-step process, with the robot trying to predict where other objects will be, then planning how to move. If something moves unexpectedly between the steps, the software can freeze up. To fix this, the team wrote new software combining the steps, so the robot constantly adjusts its planned path (arxiv.org/abs/1708.01267). Two laser scanners let their robot detect
objects such as furniture, and a motion capture system tracked human positions using markers stitched into helmets that volunteers wore. Every tenth of a second the robot scanned for changes, then updated its predictions and trajectory, all while remaining fastidiously polite. The team tested their robot in a 15-by-20-metre hallway with rooms on both sides. It was able to avoid bumping into people when someone was walking towards it, and when two people were passing on either side. It also yielded to a person emerging from a doorway. Aylin Woodward n
“The robot mimics our manners – it has to reason what a human would like to do, and react”