Posts Tagged ‘problem’

Science behind the headlines – beyond seven billion people

// December 9th, 2011 // 1 Comment » // Science Communication

We reached a big milestone last month as the world’s population exceeded seven billion people for the first time. Looking behind the headlines was Paul Willis at the RiAus and a panellist of scientists and journalists on Tuesday (event details here.)

In the 20th century we added five billion people to the Earth. Before that, we had only added two billion in total. Part of the reason is a decreased death rate, due to better medical facilities, coupled with an increase of food made possible by the Haber process that produces nitrogen fertiliser from nitrogen in the air. The chemistry makes it possible to, on some level, make food from air.

But population increase is not exponential. The UN expects the population to level off at 10 billion in the next fifty years, after a dramatic decrease in fertility, which no one anticipated.

“It is unconscionable to have a policy to increase mortality!” says Graeme Hugo, Director of the Australian Population and Migration Research Centre at the University of Adelaide. “The only way forward is to decrease fertility, that’s the only thing on the table.”

The world has done very well to reduce fertility, halving it since the 1970’s.

However, in some areas of Africa and isolated pockets in Asia it is not dropping as fast as expected. Two years ago East Timor each woman was having around eight children. The continued high fertility may be because we’ve taken our foot off the pedal when it comes to efforts like increasing contraceptives, women’s education and emancipation.

Beyond numbers

But it’s not all about the numbers, and that was the key point the scientists spoke about on Tuesday. Population is a complex issue, and has to be considered in connection to age and spatial distribution and consumption of goods.

The cost of looking after an aging semi-majority (the baby boomers) is a worry for some political movements. Balanced age groups are important to ensure the number of dependents and the number of workers is stable.

Migration may not change the global numbers, but it’s important for people are spread out in the right way. That means considering how many people a local environment can sustain in terms of food and water.

Consumption is also critical. One baby born in the United States consumes the equivalent of 30 babies born in Africa according to Udoy Saikia, School of the Environment, Flinders University (here’s a relevant link.) “People in developed countries should limit their consumption,” says Hugo. “In many developing countries, consumption needs to go up because they’re not consuming enough to be healthy.”

One way for more developed countries to limit consumption is to go vego. A more vegetarian diet is able to support more people for the same number of resources. Bring on the lentils!

This Tedx talk on the topic, I can’t recommend it enough.

Magic bullets

Scientists agreed that coverage of the seven billion people story has been pretty good overall, far better than stories about migration.

One issue they mentioned was the trend to look for a magic bullet, fixing just one thing to solve the whole population problem. It’s also hard for journalists with limited inches to talk about all the factors in a complex issue like population science.

Stopping population growth won’t work unless you take consumption into account, as well as the other factors. There needs to be a holistic approach. That doesn’t end (or even start) with policy – everyone needs to make a decision to change their consumption.

Australia

How many Australians should there be? There is no magic number where everything will fall into place. There are definite demographic problems regarding aging populations and dispersion (or lack thereof).

The scientists agreed we need a policy that allows for sustainable growth. They said it would devastate Australia if we stopped population growth tomorrow, but it would be also devastating to have uncontrolled growth.

“Every day we waste about 40% of the food (in Australia),” says Saikia. “There is some hope that the 10 billion population can survive very well, depending on distribution and consumption.”

Paul Willis summed up by asking whether Australian’s should “be concerned, not alarmed.” It’s not the end of the world, but we do need major changes and responses to population dynamics, says Hugo. “Be concerned, AND alarmed – about consumption,” says Saikia.

This post was also featured on the RiAus website.

Exploring the blurry line between colony and individual

// August 3rd, 2011 // 1 Comment » // The Realm of Bizzare

I found this great post on the Portuguese man-o-war, known as the bluebottle in Australia, over at Deep Sea News the other day. It’s eating a fish!

The post also said:

Remember this species is colonial and made of four different polyps or zooids, working in unison and dividing labor. The bladder is a single polyp called a pneumatophore. The long tentacles are dactylzooids used for fishing. The dactylzooids bring the fish up to another set of zooids, gastrozooids, responsible for digestion. Last, there is set of zooids, gonozooids, in charge of reproduction.

So it looks like a jellyfish, but it ain’t. It’s a colony of four specialists working together, each with their own nervous system but incapable of living by themselves.

Bluebottle on Woolongong Beach, NSW. Image by Fiona Wilkinson

As I was doing a bit of research about bluebottles and how they sting even when dead and dried up, I came across an interesting question. How do they reproduce? If the gonozooids are responsible for getting jiggy with it, don’t they just make more gonozooids? Where do the rest of the polyps come from?

Well, no one really is a hundred percent sure. I guess that’s fair enough, studying a swarm (a navy) of man-o-wars during mating season doesn’t sound too good. But here’s what they think.

A gonozooid from one man-o-war will make sperm which combines with an egg from another man-o-war gonozooid. Hey presto, you’ve got fertilisation and one embryo – which will become the bladder polyp at the top. That embryo divides several times, then reproduces asexually to make more zooids, which bud out of it. The budding polyps will become either tentacle, digestion or reproduction individuals.

That’s where I got confused. Does this mean that each of the zooids actually come from a single polyp? Are they just differentiated forms of the original polyp, specialised for their particular role? How is this different to a human embryo producing heart cells?

One explanation uses phylogenetics – comparing organisms to see how similar and different they are. Each zooid is similar to solitary Cnidaria (the phylum that includes jellyfish, coral and bluebottles), so can be considered an individual in its own right and a bluebottle as a colony.

But if we define an individual as something with similarity to other individuals, then all the cells of a multicellular organism would be individuals. Are individual humans really colonies of individual human cells? Really, the microbes on and in you outnumber your human cells 10 to one, so you’re more like a walking microbial factory anyway.

White poplars, a kind of aspen, form clonal colonies. Image by Jacob Halun

I think we have a very human-centric model for defining individuals, which is not surprising really. But most species on the planet don’t reproduce like we do, the boundaries between individual and colony are much less clear.

Take aspen trees, which can grow by seeds (sexually) or by underground runners which sprout a tree-clone (asexually.) Over time the runners can decay separating the trees. How can we tell if the trees are individuals or clones, and if we can’t, how do we study adaptation and natural selection?

Tasmania has these Huon pines that are the oldest genetically identical stand of trees which has lasted 10,000 years. Each tree lives about 2,000 years, but the original tree renews itself through genetic clones. Tassie also has the oldest genetically identical plants, clones of King’s lomatia estimated to be at least 43,000 years old.

Strawberries do it too, as do fungus. A single specimen of Armillaria solidepes was found in Oregon the size of 1,220 football pitches and estimated at 2,400 years old. It’s one of the largest organisms in the world.

Where does the individual end and a colony begin? Looking at all the bizarre stuff out there, I can’t help but wonder if we’re the weird ones.

ResearchBlogging.org

Clarke, E. (2010). The Problem of Biological Individuality Biological Theory, 5 (4), 312-325 DOI: 10.1162/BIOT_a_00068

Read it at the homepage of Ellen Clarke






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