Origin of the Goldfish
The goldfish (Carassius auratus auratus) you see in pet shops are the result of centuries of selective breeding.
The ancient Chinese have been rearing wild Prussian carp (Carassius gibellio) as food fish for thousands of years. During the Tang Dynasty (618-907), it was popular to raise carp in ornamental ponds. Natural genetic mutation produced individuals that had a yellowish hue to them, which was preferred over the natural silver coloration.
By the Song Dynasty (960-1279), the domestication of goldfish was established. Further genetic mutations caused for stronger oranges, reds and yellows to appear. Because these fish were kept in the safety of a pond, the conspicuous metallic colors did not disadvantage their survival.
The Ming Dynasty (1368-1644) saw the raising of goldfish indoors. This led to the development of many fancy strains, greatly changed from their wild shape. Protruding eyes, double tails and many unusual traits were emphasized through selective breeding, leading to many unique varieties of the one species.
Goldfish are still being developed today, with around 300 breeds recognized in China. Some varieties have been so physically changed that they are unable to survive outside of the aquarium. If introduced to the wild, domesticated goldfish can hybridize with certain species of carp. Within three generations, the hybrid fish revert back to their original coloration.
The human brain is able to identify individuals’ voices by comparing them against an internal ‘average voice’ prototype, according to neuroscientists.
A study carried out by researchers at the University of Glasgow and reported in the journal Current Biology demonstrates that voice identity is coded in the brain by reference to two internal voice prototypes – one male, one female.
Voices that have the greatest difference from the prototype are perceived as more distinctive and produce greater neural activity than voices deemed very similar.
The researchers in the Institute of Neuroscience & Psychology conducted the study by generating a voice prototype through morphing 32 same-gender voices together resulting in a smooth, idealised voice with few irregularities.
They then generated different voices by altering the ‘distance-to-mean’ of the prototype voice – for example, changing the tone and pitch or morphing two or more voices together.
Using functional Magnetic Resonance Imaging (fMRI), the researchers were able to see increased neural activity the further from the prototype the voices were.
Professor Pascal Belin said: “Like faces, voices can be used to identify a person, yet the neural basis of this ability remains poorly understood. Here we provide the first evidence of a norm-based coding mechanism the brain uses to identify a speaker.
“The research indicates this is a similar process for the identification of faces, where the brain also uses an average face to compare against other faces it encounters in order to establish identity.
“So, rather than having to remember each single voice it hears every day for a lifetime, the brain facilitates the task of identification by remembering only the differences from the prototype it stores.
“It leads to a range of interesting and important questions, such as whether the prototypes are innate, stored templates or whether they are subject to environmental and cultural influences. Could the prototype consist of an average of all voices experiences during one’s life?”
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