When it comes to human life, we never think about culling the herd, instead the goal is to keep as many people alive and healthy as possible.

But in nature, that isn't the best approach. Some plant diseases attack trees and crops and can hurt lumber and food production, but pathogens that kill tree seedlings can actually make forests more diverse.

Policy makers and amateur psychology pundits think "necessity is the mother of invention" - and sometimes it is, that is why that became a saying, but plain old opportunity matters a lot. Natural gas had been around for 70 years, for example, and the United States has plenty of coal, but hydraulic fracturing, a modern form of extraction, has made natural gas cheaper and led to reduced greenhouse gas emissions, a competitive advantage and a 'win' for the environment - it was developed due to opportunity, not necessity.

As baby boomers, originally the children born in 1946, after soldiers returned home from World War II in 1945 but later extended out to be an entire generation, move into old age, the financial burden of Alzheimer's disease in the United States will skyrocket to $1.5 trillion from current  from $307 billion
estimates, according to health policy scholars at the USC Leonard D. Schaeffer Center for Health Policy and Economics.

According to the U.S. Census Bureau, in 2012, 43.1 million Americans were 65 and older, constituting 14 percent of the population. By 2050, that number will more than double to 83.7 million, constituting 21 percent of the population.

Blaming 'Jordan syndrome' doesn't really cut it. British celebrity Katie Price (R) on the red carpet before the start of the Vienna State Opera Ball in Vienna, Austria, 11 February 2010. Robert Jaeger/EPA

By Jacqueline Sanchez Taylor, University of Leicester

Acute rejection after kidney transplantation occurs in about 15% of patients despite immunosuppressive therapy and this rejection is usually heralded by an increase in the patient's serum creatinine, a marker of kidney function. A kidney biopsy is then performed to confirm whether rejection is taking place.

Yet elevated creatinine is not sufficiently sensitive to identify all early rejection or specific enough to prevent some unnecessary kidney biopsies, so a noninvasive means of identifying acute rejection is needed.

Sharon Stone, in Basic Instinct, dramatized the catastrophic actions of a clever yet unhinged woman. EPA/ Peter Foley

By Suzie Gibson

Mental illness and women’s sexuality are frequently aligned – on screen and off. The father of psychoanalysis, Sigmund Freud, pathologized women’s sexuality. Indeed, his definition of a woman as someone lacking a penis has underwritten depictions of women’s sexuality.

Countless novels, films and TV programs continually pathologize women through and because of their sexuality.

10 Earths could be laid across the diameter of the gigantic sunspot in AR2191 during its previous rotation, captured on October 23, 2014. NASA’s Solar Dynamic Observatory

By Paul Cally, Monash University

The largest sunspot seen in 24 years is rotating back to face the Earth, and it looks to have grown even bigger.

Rosetta: Firing harpoons in space. ESA/ATG medialab

By Alan Fitzsimmons, Queen's University Belfast

The first attempted landing on the surface of a comet is a huge landmark in the history of space exploration that will not only uncover further details about comets but could unlock further clues about the origins of our solar system and the development of life on Earth.

Forget the Higgs Boson, the Landing on Comets, Missions to Mars, the Genome Project, Nanostructures and all that. This start of this new millennium looks like the dark ages to me if I have to gauge it from discussions I overhear in public places. 

A new active asteroid called 62412 has been located in the Solar System's main asteroid belt between Mars and Jupiter. It is the first comet-like object seen in the Hygiea family of asteroids.