Machine learning reveals how often fish schooling evolved—and repeatedly disappeared
from Phys.org
Scientists have used new machine learning techniques to investigate a topic no one has ever found a way to study: the evolution of fish moving together in schools across thousands of species. The new paper, published Nov. 6 in the Proceedings of the National Academy of Sciences, is among the largest studies of the evolution of any behavior ever conducted in any group of species, according to the authors. The research shows that behaviors, which have previously been difficult to quantify, can be studied at a large evolutionary scale.
explained
Machine learning is a field of artificial intelligence focused on statistical algorithms that learn from data and generalise to unseen data, performing tasks without being explicitly programmed. It rests on statistics and mathematical optimisation, and deep learning's neural networks have surpassed many earlier approaches. Because of this dominance, the terms machine learning and artificial intelligence are now often used interchangeably, though they are not synonymous.
Schooling is costly as well as useful: it protects from predators and saves energy, but it also means competing for food and spreading disease. Whether the benefits win depends on a species' habitat and lifestyle, so it can be gained or lost.
so what
Behaviour leaves no fossils, so it is hard to study in evolutionary time. If machine learning can score behaviour at this scale, researchers can ask the same kind of question about migration, mating displays and other traits that are hard to measure.
Trump and Netanyahu reportedly clash over whether to resume military action against Iran
the gist
Israeli reports also say the cabinet directed the military to prepare for a possible new attack on Iran.
so what
The United States and Israel have been closely aligned on Iran's nuclear programme and regional threats, so open disagreement between their leaders over military strategy is unusual and closely watched. Whether to resume strikes is a decision with consequences for shipping, oil markets and the wider Middle East.
fun fact
Benjamin Netanyahu has served as Prime Minister of Israel for more years in total than any other person.
world cultures & travel·Wikivoyage·classic9th–15th century · Siem Reap, Cambodia
Angkor was the largest pre-industrial city on Earth, covering about 3,000 square kilometres
the gist
Angkor, near Siem Reap in northern Cambodia, was the capital of the Khmer Empire, which ruled much of mainland Southeast Asia between roughly the 9th and 15th centuries. At its height the city spread across about 3,000 square kilometres, making it the largest pre-industrial city on Earth by area. Its growth depended on water: huge reservoirs called barays, along with canals and embankments, stored monsoon rain and carried it to rice fields. That system let farmers harvest more than once a year and fed a very large population through the dry season. The temple complex of Angkor Wat, built in the early 12th century, is the best-known monument and still stands at the heart of the park.
how it works
The Khmer kings built enormous rectangular reservoirs that caught monsoon rain during the wet season. Earthen dykes and canals moved that water into rice paddies, so farmers could grow crops across much of the year. The surplus food supported craftsmen, builders and the workforce that raised the temples.
so what
Angkor shows how a society without industrial machinery could build a city on a scale that rivals modern metropolises, using engineering and water management instead. Some historians link its decline to drought, flooding and shifts in its water systems, which makes it a long-running case study in how cities depend on managing water. The site is a UNESCO World Heritage Site and one of the most important archaeological landscapes in Southeast Asia.
fun fact
The outline of Angkor Wat appears on the national flag of Cambodia.
more on this
background
Angkor (Khmer: អង្គរ [ʔɑŋkɔː], lit. 'capital city'), also known as Yasodharapura (Khmer: យសោធរបុរៈ; Sanskrit: यशोधरपुर), was the capital city of the Khmer Empire, located in present-day Cambodia. The empire flourished from approximately the 9th to the 15th centuries. The site of Angkor has a variety of religious temples, libraries, moats, and other buildings. These other buildings could have been used by officials to the grand palace housing the Khmer king. Those constructed outside the main complex were not made of stone. One of the more visited places in Angkor is Angkor Wat, a temple complex that is one of Cambodia's tourist attractions.
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