Just a reminder that fat has a purpose...

The Chimp Crawl

A new report due out in PNAS measured the efficiency of bipedal versus quadripedal gaits in chimps. The authors find that in individual chimps, bipedal walking was more energy efficient than differed in energetic cost from quadripedal walking, with individual differences in anatomy and gait determining the more efficient method. These findings suggest that biomechanical changes and the accompanying energetics may have spurred the development of human bipedalism, which is far more efficient than either chimp gait.

So that's why the bear crawl is so painful...

Eat those fruits and vegetables!

First in a series devoted to reducing risks of death.
If you had any doubt that eating fruits and vegetables is beneficial to your health, maybe some data will convince you.
Sidebar: You can skip this on first read, but here are some links to potentially unfamiliar terms. If you aren't familiar with study designs, have a quick here. If you aren't used to thinking about relative risk (don't confuse them with odds ratios), have a look here. Most of the data presented below came from prospective cohort studies with large cohorts and long-term follow ups. I chose primarily meta-analyses to get better power and lower bias (although you may want to check the citations to see the specifics of how studies were selected for inclusion).
The figure below summarizes a meta-analysis of prospective cohort studies (Hu & Willett, 2002) examining the effect of eating nuts, fruits and vegetables or whole grains on cardiovascular disease. The relative risks were derived from the comparison of the incidence rates between the highest and lowest consumption groups (quintiles, quartiles or specific intake categories as per specific study) and were adjusted for nondietary and/or dietary covariates. These are huge effects.

So it's pretty clear that eating nuts, fruits and vegetables or whole grains can reduce your risk of cardiovascular disease. However, the comparison above is basically between eating lots versus eating little of any of these food categories. You might be wondering whether there is a dose-dependence for reducing risk. The following figure comes from another meta-analysis of prospective cohort studies (He et al., 2007), and focuses on fruit and vegetables. Here the risk ratios were derived from comparing the highest categories of fruit and vegetable consumers (3-5 servings/day and >5 servings per day) against lower intakes (<3 and="" cardiovascular="" class="separator" day="" disease.="" div="" eat="" fruits="" group="" lower="" more="" of="" risk="" servings="" style="clear: both; text-align: center;" the="" vegetables="" you="" your=""> What about other diseases? Well, it probably shouldn't surprise you that eating fruits and vegetables also reduces your risk of stroke, the third leading cause of death (nipping at the heels of CHD and cancer). The figure below summarizes a meta-analysis of prospective cohort studies (He et al., 2006) on the effects of eating fruits and vegetables on stroke. Note that were looking only at the top consumers (as in the immediately preceding figure). Again, we're seeing a nice dose-dependent effect of eating fruits and vegetables on reducing your risk of stroke (both ischaemic and haemorrhagic).

This dose-dependence is more clearly illustrated in a similar meta-analysis (Dauechet et al., 2005). The following is a summary figure, which further breaks down the data by fruits alone, vegetables alone and fruits+vegetables. The size of the bubbles is inversely proportional to the variance of the relative risk of each study, bigger bubbles=more reliable study. Looks like it "eat your fruits and vegetables, but more of those fruits".

I'm off to eat a bushel of apples.

Evolution of running

Figure 2 from a fascinating paper about the evolution of endurance running by Dennis Bramble and Daniel Lieberman.

Saturday round-up

The Inner Life Of A Cell (animation by John Liebler/XVIVO)
The full version is here, and includes commentary explaining what the scenes are. More information here, which includes a higher resolution version of the short. This is awesome, do not miss it. Via Street Anatomy, which is also worth a visit.

More beautiful scientific artwork can be found at bioemphemera and Morbid Anatomy. 3D animation of a normal childbirth here. Click that at your own risk.

Remarkable stem cell research showing that mature skin cells can be coaxed into becoming cells with embryonic stem cell capacities (blurb in the Times, and direct links to the results from the Kyoto group and the MIT group). An explanation from Rudolph Jaenisch, who leads the MIT group:

Brain food

Food for thought is an interesting review by anthropologist William Leonard covering the idea that shifts in food preferences over the course of human evolution were driven by the requirements of bigger brains, which itself may have been driven by climate induced ecosystem change. A more in depth review by Leonard and colleagues with references to the primary literature: Effects of Brain Evolution on Human Nutrition and Metabolism.

The work of primatolgist Katherine Milton provides very good background reading. The Critical Role Played by Animal Source Foods in Human (Homo) Evolution is a good place to start.

Some nice images here.