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Study: Smelling Sense is Similar in Humans, Insects

Locusts farmed for human consumption are seen at the Kreca breeding facility in Ermelo, the Netherlands. Reuters
Locusts farmed for human consumption are seen at the Kreca breeding facility in Ermelo, the Netherlands. Reuters
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Study: Smelling Sense is Similar in Humans, Insects

Locusts farmed for human consumption are seen at the Kreca breeding facility in Ermelo, the Netherlands. Reuters
Locusts farmed for human consumption are seen at the Kreca breeding facility in Ermelo, the Netherlands. Reuters

A research team from the Norwegian University of Science and Technology (NTNU) found that the process of "olfactory information" is similar in humans and insects.

By using the brain of a cotton bollworm as a model, the branching patterns and coding mechanisms the researchers detected in the small model brain seem to be relevant not only for insects, but also for mammals—which include people. The findings were published in the journal eLife on October 10.

"We find striking similarities in the structure and function of the olfactory system across different organisms. The similarities are probably related to the fact that the olfactory system is evolutionarily the oldest of all sensory systems," said Xi Chu, a researcher in Chemosensory Laboratory at NTNU and senior author on the study.

The researchers studied second-order olfactory neurons in male cotton bollworms. The males carry signals from the primary olfactory center to other areas of the brain, where the signals are further interpreted to provide the correct responses. They're strangely similar to neurons, called mitral cells, in humans and other mammals.

"When we smell something, it's because certain molecules that are dispersed in the air first activate sensory neurons in the olfactory epithelium. This is an area in the nose that captures odor molecules and carries them further into the brain's primary olfactory center. Here, the sensory terminals form a kind of map, so neurons that have the same type of olfactory receptor accumulate within spherical structures called glomeruli," Chu explained.

"Insects have a similar system of sensory olfactory neurons that form glomeruli in their antennal lobes. The similarity also applies to second-order olfactory neurons that send signals from the primary olfactory center to higher-order areas," he added.

The various odors are represented in the form of a collection of non-overlapping glomeruli in the primary olfactory center. But they are arranged in a quite different way in the subsequent second-order centers. In both insects and humans, the terminals of second-order olfactory neurons cover relatively large areas that partly overlap, he explained.

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China's Population Falls for 3rd Straight Year

A delivery worker sits on a delivery vehicle along a street in Beijing on January 17, 2025. (Photo by Jade GAO / AFP)
A delivery worker sits on a delivery vehicle along a street in Beijing on January 17, 2025. (Photo by Jade GAO / AFP)
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China's Population Falls for 3rd Straight Year

A delivery worker sits on a delivery vehicle along a street in Beijing on January 17, 2025. (Photo by Jade GAO / AFP)
A delivery worker sits on a delivery vehicle along a street in Beijing on January 17, 2025. (Photo by Jade GAO / AFP)

China's population fell last year for the third straight year, its government said Friday, pointing to further demographic challenges for the world's second most populous nation, which is now facing both an aging population and an emerging shortage of working age people.
China's population stood at 1.408 billion at the end of 2024, a decline of 1.39 million from the previous year, The Associated Press reported.
The figures announced by the government in Beijing follow trends worldwide, but especially in East Asia, where Japan, South Korea, Hong Kong and other nations have seen their birth rates plummet. China three years ago joined Japan and most of Eastern Europe among other nations whose population is falling.
The reasons are in many cases similar: Rising costs of living are causing young people to put off or rule out marriage and child birth while pursuing higher education and careers. While people are living longer, that's not enough to keep up with rate of new births.
Countries such as China that allow very little immigration are especially at risk.
China has long been among the world’s most populous nations, enduring invasions, floods and other natural disasters to sustain a population that thrived on rice in the south and wheat in the north. Following the end of World War II and the Communist Party’s rise to power in 1949, large families re-emerged and the population doubled in just three decades, even after tens of millions died in the Great Leap Forward that sought to revolutionize agriculture and industry and the Cultural Revolution that followed a few years later.
After the end of the Cultural Revolution and leader Mao Zedong's death, Communist bureaucrats began to worry the country’s population was outstripping its ability to feed itself and began implementing a draconian “one child policy.” Though it was never law, women had to apply for permission to have a child and violators could face forced late-term abortions and birth control procedures, massive fines and the prospect of their child being deprived an identification number, effectively making them non-citizens.
Rural China, where the preference for male offspring was especially strong and two children were still ostensibly allowed, became the focus of government efforts, with women forced to present evidence they were menstruating and buildings emblazoned with slogans such as “have fewer children, have better children."
The government sought to stamp out selective abortion of female children, but with abortions legal and readily available, those operating illicit sonogram machines enjoyed a thriving business.
That has been the biggest factor in China’s lopsided sex ratio, with as many as millions more boys born for every 100 girls, raising the possibility of social instability among China’s army of bachelors. Friday’s report gave the sex imbalance as 104.34 men to every 100 women, though independent groups give the imbalance as considerably higher.
More disturbing for the government was the drastically falling birthrate, with China’s total population dropping for the first time in decades in 2023 and China being narrowly overtaken by India as the world’s most populous nation in the same year. A rapidly aging population, declining workforce, lack of consumer markets and migration abroad are putting the system under severe pressure.
While spending on the military and flashy infrastructure projects continues to rise, China’s already frail social security system is teetering, with increasing numbers of Chinese refusing to pay into the underfunded pension system.
Already, more than one-fifth of the population is aged 60 or over, with the official figure given as 310.3 million or 22% of the total population. By 2035, this number is forecast to exceed 30%, sparking discussion of changes to the official retirement age, which one of the lowest in the world. With fewer students, some vacant schools and kindergartens are meanwhile being transformed into care facilities for older people.
Such developments are giving some credence to the aphorism that China, now the world’s second largest economy but facing major headwinds, will “grow old before it grows rich.”
Government inducements including cash payouts for having up to three children and financial help with housing costs have had only temporary effects.
Meanwhile, China continued its transition to an urban society, with 10 million more people moving to cities for an urbanization rate of 67%, up almost a percentage point from the previous year.