Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.

    The gene comes in two versions, one of which is found in 99 percent of Europeans. The other is found in 93 to 100 percent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

    Scientists have changed the color of a dark-striped zebra-fish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra-fish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.

    It appears that, like the golden zebra-fish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.

    However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra-fish genes.

    Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.

    But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

    Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

    The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

    A chip inserted in a young quadriplegic's (四肢麻痹患者) brain is already improving his quality of life. Soon the benefits may be more widespread.

    A 25-year-old man unable to move from the neck down recently did what many assumed impossible. After a knife attack that had left him paralyzed, all he could move was his head, which he used to push a switch and call for a nurse. And he could turn his wheelchair by blowing into a straw near his face. That was it.

    Then last June, a Foxborough (Mass.) company called Cyber Kinetics opened the man's skull and inserted a special chip no larger than a baby aspirin. That insert has given him a few additional and precious abilities. When connected to a special computer via a cable, the chip translates the young man's thoughts into commands that let him move a cursor across a PC screen and open e-mail. He can draw a circle with a computer painting program. And he can use a robotic hook(钩) to perform simple tasks like picking up a candy and sliding it across a table.

    All he has to do is to think.

    Several new studies have begun or been completed in the past year. In fact, more than half of the scientific papers in this field, called brain-to-computer interaction (BCI), have been published in the past two years, notes Jonathan Wolpaw, a research physician at Wadsworth Center, the New York State Health Dept.'s research laboratory.

    Brain surgeries (手术) are no longer rare: Thousands of Parkinson's disease patients have had special devices inserted in their brains to ease uncontrollable shaking and other symptoms. The inserts themselves have improved, so the body doesn't reject them as furiously(猛烈地). And significant development has been achieved in software used to interpret the brain's signals and change them into commands understood by computers.

    But increased demand for thought technology remains the biggest reason for the field's progress. Today, 4 million Americans live with paralysis according to the Christopher Reeve Paralysis Foundation.

    Scientists hope that thought technology will reduce the impact of such disabilities. People with spinal-cord injuries, for example, often lose their ability to walk because the communications network between their brain and their legs has been interrupted. The brain still commands the leg muscles to move, but they don't hear its orders.

    Thought technology, scientists hope, will bridge this communications gap. "Our goal is for you to see paralyzed people eating at a restaurant and for you not to know that they are paralyzed," says John Donoghue, founder and chief scientific officer at Cyber Kinetics.

    Dyslexia(失读症) is a learning disorder, it interferes with the ability to recognise words, and for some readers to understand what they have read.

    Experts say dyslexia affects about five to ten percent of the population of the United State. Researchers have long known that people with dyslexia write or read words and letters backwards in the wrong order.

    But a new study shows that people with dyslexia may have trouble redirecting(重新传入) their attention between senses, from seeing something to hearing something. The study suggests something that might help dyslexic people learn more quickly — play video games.

    Vanessa Harrar of Britain's University of Oxford led the study. She reported the findings in the journal Current Biology. The study suggests that dyslexic people may have trouble moving quickly from what they read to what they hear. Doctor Harrar calls this a "sluggish shifting of attention across the senses."

    "So, if you are trying to read something and then trying to listen to somebody who's reading aloud and you're trying to follow along with what they are reading -- they have to switch their attention from hearing what they are saying to looking at the piece of paper and back again. So we found they have quite sluggish shifting of attention across the senses," said Harrar.

    In the study, Doctor Harrar tested 17 people with dyslexia, and 19 others without reading problems. The volunteers were asked to push a button as quickly as possible when they heard a sound, saw a light or experienced both together. Doctor Harrar compared the speed of their reactions.

    She found that people with dyslexia were just as fast as the others when they saw only a picture or heard only a sound. But the dyslexics had a slower reaction time when they heard a sound and saw a picture at the same time.

    Doctor Harrar feels like playing action video games could help dyslexic people shift from seeing to hearing more quickly. She adds that images in video games force the eyes to move and focus quickly.

    "Video game types of things pop out of here and there, they move your eyes around the screen quite quickly in response to things quite quickly, and the more you play a video game the faster you get that kind of thing. So, the video game is really training the attention system to move quickly," said Harrar.

    The study also shows that dyslexic people have the most difficulty going between what they saw and what they heard, this may have an effect on how dyslexic children are taught how to read.

    When children learn the alphabet, they usually see the letter first and then hear the sound, or they see and hear the letter at the same time. The study shows that dyslexics might learn more quickly if they hear the sound of a letter or word first before seeing it.

    As Simon Kindleysides, 34, took his first step in the London Marathon in April, he felt as if magic was in the air.

    "As we were walking toward the first mile, we actually started joining all the runners," he said. "Everyone was on the streets, cheering, and that was a magical moment." As time went on, the crowds and other racers spread around. Kindleysides and his team of eight supporters continued walking.

    Kindleysides, who is paralyzed(瘫痪的)from the waist down and typically uses a wheelchair, was equipped with an exoskeleton(体外骨骼)to help him walk. His supporters walked with him to change the batteries in his exoskeleton so he could keep moving.

    In 2013, Kindleysides was diagnosed with a brain tumor (肿瘤) that was growing in a way that pressed on certain nerves, leading to him losing feeling in his legs. He was told he would never walk again. Before his paralysis, the London­based singer and dancer had "always wanted to run a marathon," he said, but he never made the plan to do so­­until this year.

    During the London Marathon, the last two miles were the hardest. "At that point, I was exhausted. It was freezing cold, and I was hurting emotionally," Kindleysides said. But he kept going. "I didn't want to let people down. I had a team of eight, and I was raising money for The Brain Tumour Charity," he said. "I didn't want to let them down, myself down, and I thought if I would get this far, I would have to continue."So he continued and made history as the first paralyzed man to complete the London Marathon on foot.

    Then, recovering at home, he shared his accomplishment with his three children. "They used to say I'm the only dad in their whole school who's in a wheelchair, and now they say I'm their dad, the only one who has walked a marathon," he said.

    Kindleysides is training to complete three more marathons next year, including the London Marathon again.

    Last night, when I went to see my grandmother, she was sitting alone at the nurse station with her word search book. My grandmother was sitting at the desk with her book but no pencil just staring at the letters as if she was trying to find the word. I came to her and said hello.

    Usually, she at least knows I am connected to her somehow but this time, she looked at me with doubt. I introduced myself and told her that I was her granddaughter. "I don't know who you are," she said." Do you want to go outside?" I asked. "okay," she said.

    We got her things and I wrapped it all in a blanket we would use as a tablecloth. I asked her if she could hold it while I pushed her wheelchair and held her cup of tea.

    She held her hands out and I placed the cloth bundle (捆) on her lap. I put the cloth on the table and she helped smooth it down-then I put the rest of the items on the cloth.

    Now she was just staring at me as if confused, as if trying to figure me out. "Do you know who I am?" I asked. She said, "I don't really know." "I am your granddaughter," I said. "I am not sure what that is. I don't know, I don't know you," she said.

    I think of my friend whose mother has not known him for years, has no recollection (记忆), and doesn't speak any more. It is a painful sight for all those living who remember. I am grateful that my grandmother is still so present. I have a sinking feeling that our days are numbered.

    For now, she is still here, still says thank you, and still loves me from a deep and secret place. Tomorrow, I will see her and she may or may not know me-and that will be okay. I still know her.

On a recent Wednesday, archaeologists announced a groundbreaking discovery that challenges our understanding of early human capabilities. They have unearthed what is believed to be the oldest wooden structure ever found, dating back nearly half a million years. This discovery at Kalambo Falls in northern Zambia, near the border with Tanzania, suggests that our ancestors were more technologically advanced than previously thought.

The wooden structure, which is exceptionally well-preserved, dates back at least 476,000 years. This timeline predates the emergence of Homo sapiens, as detailed in a study published in the journal Nature. The wood shows evidence of having been cut and shaped using stone tools, indicating a level of craftsmanship that was not previously attributed to these early humans.

The structure, which is thought to have functioned as a walkway or platform elevated above the seasonally wet ground, demonstrates a purposeful construction technique. A collection of wooden tools, including a wedge and a digging stick, were also found at the site, further supporting the idea of a developed woodworking tradition.

Larry Barham, an archaeologist at the University of Liverpool and the lead author of the study, described the structure as involving "the intentional shaping of two trees to create a framework of two interlocking supports." A notch was cut into one log, and another tree was shaped to fit through this notch, providing stability to the structure.

The use of wood by early humans was already known, but it was typically associated with basic tasks such as starting fires or hunting. However, the discovery at Kalambo Falls indicates a more sophisticated application of woodworking skills. Barham explained, "The structure involves the intentional shaping of two trees to create a framework of two interlocking supports," which required a level of planning and execution that suggests a higher cognitive ability.

The preservation of the wooden structure is remarkable, given that wood typically decays over time, leaving little trace for archaeologists to study. The high water levels at Kalambo Falls are believed to have played a crucial role in preserving the structure for centuries.

These findings from Kalambo Falls not only provide evidence of an early human ability to manipulate their environment but also suggest a more complex cognitive capacity among these early humans than what has been inferred from stone tools alone. Barham concluded, "The finds from Kalambo Falls indicate that these earlier humans, like Homo sapiens, had the capacity to alter their surroundings, creating a built environment." This discovery underscores the need to reassess our understanding of early human technological and cognitive development.