Birds' feathers are some of the most strikingly variable animal characteristics that can be observed by the eyes. The patterns that we see in birds' feathers are made up of combinations of scales, bars, and spots.

    We already know why birds have colored feathers. Generally, the color of feathers may protect a bird from being noticed by the enemy in the environment, or it can make a bird more appealing to potential mates by helping them to stand out. These aspects are well known. A greater mystery has been how the patterns are created.

    Dr. Ismael Galván and his team studied the color of feathers to see what types of colors were present in birds' complex feather patterns. The study shows they mainly consist of two types of colors: melanin（黑色素）, which produce a range of black, grey, brown, and orange color, and carotenoids（类胡萝卜色素）, which are used to create brighter colors.

    Birds cannot produce carotenoids on their own. For feathers with bright colors, birds must consume food items that contain these paints, and the carotenoids circulate through the blood and to the feather. Melanin, on the other hand, is produced by special cells in the birds' bodies.

    The team found that about 32% if the species studied have complex color patterns, with the vast majority of these complex patterns produced by melanin rather than carotenoids. If the birds were artists, they would use carotenoids as a broad brush to produce color patches, with melanin as a detail paint brush to produce more complex designs.

    But a few birds are exceptions to this rule: Three bird families do have complex patterns without melanin.

    Want to stay away from colds? Put on a happy face.

    Compared to unhappy people, those who are cheerful and relaxed are less likely to suffer from cold, according to a new study. It's possible that being happy helps the body fight illnesses, say the researchers from New York University.

    “It seems that positive feelings may reduce the danger of illness,” said the study's chief researcher Sheldon Cohen.

    In an earlier study, Cohen found that people who were cheerful and lively caught coughs and colds less often. People who showed positive feelings were also less likely to tell their doctors that they felt ill.

    In this study, Cohen's study interviewed 193 adults every day for two weeks. During the interviews, the people told researchers about the happy or sad feelings they had that day.

    After the two weeks, the people were given colds by doctors and had to stay alone in a room for six days.

    The result showed that everyone in the study was equally likely to get ill. But for people who said they felt happy during the research period, their illness was less serious and lasted for a shorter time.

    Cohen believes that when people experienced positive feelings, their body may produce a chemical that helps fight illness and disease. So if you are worried about your health, look on the bright side more often.

    Sometimes it can be easy to become too satisfied when it comes to living sustainably. We may all have recycling bins in our kitchens, but here are some ways you can live more sustainably.

    ⒈Put an end to plastic water bottles and one-off coffee cups

    The only way this is going to work is that if you have reusable options you really love, invest in a great water bottle. This is an advance payment, but it will save you money in the long run. A 750ml bottle of Evian costs 90p in Tesco, meaning if you buy one every two days you could save £10 within three weeks by filling up a reusable bottle at home.

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    The high street is problematic on so many different levels. Not only are you buying items with questionable supply chains, but the carbon footprint of each product is shocking as well. Online shopping is even worse, with overpackaging for each item and the emissions from delivery trucks. The answer is to stick to reach-me-down or previously owned items as much as possible. Not only will this save you money, but there's also a sense of satisfaction in finding a hidden treasure from the flea market where you find outstanding bargains or something used, which you simply can't get from shopping in Wal-Mart or on Amazon.

    ⒊Think hard about your transportation

    Even if your car is supposedly a low-emissions model, it's still going to be a huge contribution to your carbon footprint. There are times when getting in a car can't be avoided, but if you can substitute just one flight a year with a train, one car journey a week with a bus, and one bus a month with a bike ride, you'll find that making more mindful transport decisions can easily make your day-to-day life more environmentally friendly with little effort.

    ⒋Try to buy local, seasonal produce

    You may think buying strawberries in December or courgettes in spring is no big deal, but the chemicals and fuel used to artificially copy the right environment for them to grow create harmful gas emissions. Similarly, the environmental impact of transporting produce from another country is huge. Buying from local farmers also means you can often ignore the huge amounts of packaging the supermarkets use.

    Broad Band: by Claire L. Evans. Portfolio, 2018（$27）

    Though often outnumbered by men, women stayed in the booming field of computing. In this inspiring tale, writer Evans records the contributions of some B. ROAD of the many women who aided the rise of the modern Internet. Memorable characters include Elizabeth "Jake" Feinler, an information scientist who helped researchers navigate the Arpane and Stacy Horn, who started one of the first social networks, Echo.

    The Wizard and the Prophet: by Charles C. Mann. Knopf, 2018（$28. 95）

    The human population is moving toward 10 billion—some experts think we'll nearly hit that mark by 2050. How will the earth feed, house and otherwise support such a crowd？Environmental thinkers usually fall into one of two camps: those who prefer conservation and controlling consumption, like William ems, Norman Borlaug, for example, Writer Mann carefully record the lives and thought of the founder of these two philosophies.

    A Lab of One's Own: by Patricia Fara. Oxford University Press, 2018($24. 95)

    In World War I many women in the U. K. replaced their aprons with chemical suits and stepped into previously male-only fields of science, where they led war research efforts. Science historian Fara illustrates the lives of many of these forgotten women. Although the era marked a major step forward for women scientists, many worked for small wages in an environment of discrimination. In the nearly 100 years since, women have come a long way, Fara writes, but the glass ceilings remain solid and the pipelines leaky.

    Atom Land: by Jon Buterworth. The Experiment, 2018（319. 95）

    Butterworth takes readers on an amusing journey through the unknown OMS world of particle（粒子）physics. The first stop is "Atom Land," where Butterworth explains how electrons, protons and neutrons come together to build up everything we know. As the journey unfolds, we learn about lesser-known particles. Thankfully, our ship is equipped with tools such as mathematical equations（方程式）and a "laser light" that lights up the darkest of concepts.

    The effects of coffee consumption on health have long been a subject of conflict and uncertainty. Since the 1980s, some have spoken out against coffee as harmful to health, while others have welcomed coffee for its supposed benefits to health.

    According to a scientific report, mild coffee consumption, three to five cups per day, can be taken as a healthy dietary pattern, along with other healthful behaviors. The report also says that coffee consumption helps reduce the risk of heart disease and it protects against Parkinson's disease.

    According to Dr. Donald Hensrud of Mayo Clinic, high consumption of coffee has health risks. Dr. Hensrud mentions the dangers of high coffee consumption for people with a certain illness that slows the breakdown of caffeine in the body. Some studies said that drinking two or more cups of coffee daily can actually increase the risk of heart disease in these people.

    According to conclusions from a recent study led by Dr. Gregory Marcus, a doctor from the University of California San Francisco, daily moderate consumption of caffeine, less than 4 cups, is not associated with these issues.

    Until the scientific community reaches a general agreement on the effects of coffee consumption on human health, it will be up to the individual to decide whether the benefits of drinking coffee are greater than the risks.

    When informed of these possible health benefits and harms of drinking coffee, Harwood, a high school student stated, "Even though there might be some negative effects of drinking coffee, for the most part, coffee drinking sounds good for health. Not to mention I need coffee to stay awake."