Page 12 - New Scientist

NEWS & TECHNOLOGY

The runaway US Several counties in Texas and elsewhere in the US have carried out a lot
of executions despite not having a similarly high murder rate
30 or more murders per 100,000 30 or more executions per
execution counties people, 1977-2014 100,000 people, 1977-2014

Jessica Hamzelou Instead of reflecting crime
rates, the team found that an IOWA
A HANDFUL of hotspots carry execution was more likely to COLORADO
out a disproportionate number take place in a county if another
of executions in the US, despite execution had previously been VIRGINIA
not having particularly high rates carried out there (PLoS One,
of murder. Instead, human bias doi.org/gcrqcq). SOUTH CAROLINA
TEXAS GEORGIA
seems to have led a small number This effect is known as an
of counties to become far more information cascade, says SOURCE: DOI: 10.1371
likely than others to execute. Baumgartner. Humans often Harris County
The death penalty is legal in make decisions on the basis of
31 of the 50 US states, where it is what others have done before,
handed down to some people rather than on the information says Brandon Garrett at the onwhattheybelieveothersexpect
convicted of murder. Now an in front of them. This cognitive University of Virginia. of them, says Baumgartner.
analysis of data from the 38 years shortcut makes it easier for people “The idea is that executions are “The system separates out into
since 1977 has identified the US to make what they deem to be only for the most heinous crimes places where district attorneys
counties that account for most of correct decisions, but means and deserving criminals,”says ‘don’t even try’, and where other
the country’s executions. During that people and events are not Baumgartner.“But our research DAs feel they‘have to’,”he says.
that time, 1422 people were assessed independently. Other biases shape death
executed, 513 of them in Texas. “Jury members and jurors are “Executions should only sentencing, too.“The odds of
But even within Texas, there is likely to compare their decisions be for the most heinous getting a death sentence are three
strong variation. Harris County, with others that have been made crimes, but really it’s to four times higher for those
home to Houston, carried out the within the same county, rather geographically arbitrary” who kill white people versus those
most executions, 125, during the than focusing on the individual who kill minorities,”says Radelet.
study period, while neighbouring case,”says Michael Radelet at the suggests it’s really not the worst Overall, the number of
county Montgomery had just 13. University of Colorado, Boulder. of the worst being executed. executions taking place
“We looked at whether This runaway effect has led to It’s geographically arbitrary.” across the US is declining.
execution rates were linked to many counties that no longer This is unconstitutional, Those that are carried out are
higher rates of homicide per perform executions, while some Baumgartner argues. The 14th increasingly involving untested
population,”says Frank others continue to do so at a high amendment states that everyone approaches, prompted by some
Baumgartner at the University rate.“We see hardly any counties should be equally protected by pharmaceutical firms refusing
of North Carolina.“But that that stop sentencing [people to the law. But judges and juries are to sell chemicals for the purpose
wasn’t the case at all.” death] and then start again,” muchmorelikelytoexecutebased of use in lethal injections. ■

Mount Etna may also belches out more than 7 million sulphur, making up about 70 per cent
tonnes of steam, carbon dioxide and of the material feeding the volcano
not be a proper sulphur dioxide every year. (Earth-Science Reviews, doi.org/cjbh).
The normal explanation is that gas “Only 30 per cent is molten rock,” he
volcano after all bubbles out of magma as it moves up says. Such a system is closer to a hot
the volcano’s vent. But Ferlito says spring than a conventional volcano.
ONE of the most famous volcanoes Etna would need to erupt 10 times Ferlito suggests Earth holds watery
may be misunderstood. A geologist more lava than it does to account for pockets that can feed volcanoes like
believes the material feeding Mount all the gas. Or maybe most of the Etna, in line with other evidence for
Etna’s cone is mostly water, so it is molten rock in Etna loses its gas and Earth’s interior having lots of water.
effectively a giant hot spring. But sinks without erupting. But Ferlito’s But there are simpler alternatives,
other geologists are unconvinced. MARCO RESTIVO/GETTY figures imply this would require 10 says Kayla Iacovino at Arizona State
Italy’s Mount Etna is almost always tonnes of fresh magma every second. University. She has argued that the
active. It may have spewed 70 million Instead, Ferlito argues that Etna is excess gas could come from deep
tonnes of lava in 2011 alone. But what not just fed by magma. He calculates molten rock that doesn’t enter Etna
really puzzles Carmelo Ferlito at the At first glance, Mount Etna that its deep plumbing system could (Earth and Planetary Science Letters,
University of Catania, Italy, is that Etna definitely resembles a volcano– hold lots of water, carbon dioxide and doi.org/f7wp2w). Colin Barras ■

10 | NewScientist | 20 January 2018