50 million years ago caused the first horses, already tiny in stature compared with present-day animals, to shrink 30 percent to about 8.5 pounds, the size of a house cat today, a study suggests.
Later, as the climate cooled, the horse called Sifrhippus began to grow in size, according to research in the journal Science. Scientists the University of Michigan's Museum of Paleontology used fossilized teeth to make the size estimates.
The finding, which correlates to a 10 to 20-degree change in global temperature, follows Bergmann's rule, which says that smaller animals within the same species are usually found in hotter climes. The study also may suggest that creatures alive today may shrink if global warming continues, said Philip Gingerich, a study author and the museum's director.
"I joke about this all the time -- we're going to be walking around 3 feet tall if we keep going the way we're going," Gingerich said in a statement.
From 1906 to 2005, the world has been in an "unequivocal" warming trend, according to the Environmental Protection Agency's website. The earth warmed about 1 to 1.7 degrees Fahrenheit over that time, much less than the warming trend 56 million years ago.
Matt and Kelly Grocoff have renovated their 110-year-old home in Ann Arbor, Michigan to state-of-the-art energy standards. Their energy bills demonstrate the results: They actually generate more energy from on-site renewable sources than they consume. The Grocoffs believe they now have the oldest "net zero" home in America.
There's a lot to like about this, but what I like best is that the home is green not only with respect to building energy but also with respect to transportation energy, because it is in a walkable city neighborhood of older homes on compact lots on gridded streets, with services and amenities close by. They sit within a block's walk of three schools by my count, and there is a transit line also a block away. There's a neighborhood pocket park just down their own block. There's a market, a bank branch, and several restaurants within a 10- to 12-minute walk. Yet theirs is a leafy neighborhood of mostly single-family homes.
I ran the address through the Center for Neighborhood Technology's Abogo calculator for transportation costs and emissions: an average household in the Grocoffs' neighborhood emits only half as much carbon from transportation as does an average household for the metropolitan region as a whole. This is because the Grocoffs' more central, more walkable location shortens driving distances and tends to reduce automobile trips, compared to more outlying subdivisions.
So finally we have a well-publicized green home that is also in a green location. I hope the Grocoffs begin to stress that in their materials as they move forward. And so much the better that the home fully retains its historic character. Here's the neighborhood (the large building complex in the lower left corner is two schools):
Regular readers of my work know that few things bug me more than boasts about "green" homes and other buildings placed in locations with high driving rates that wipe out whatever energy savings they achieve from superior building technology. (See my posts about a bogus "net zero" claim, and green awards for sprawl from the American Institute of Architects and even the US Green Building Council.)
You can read about the Grocoffs' energy-efficient home on their own site, on Treehugger, on annarbor.com, or on GreenovationTV, which Matt Grocoff founded. Or you can just take the three-minute video tour, courtesy of a local TV station. The home looks not just green, but also a very nice place to live.
