“Every few seconds, you get an updated image, so you can advance a tube
through the brain and watch its progress,” says Mark Bernstein, head of
neurosurgery at the Toronto Hospital and part of the team developing the
Image-Guided Minimally Invasive Therapy (IGMIT) machine.

Magnetic resonance imaging (MRI) uses an intense magnetic field to make
hydrogen atoms absorb and emit radio waves. These signals are picked up by a
scanner, giving a detailed picture of what is happening inside the body.

Standard MRI machines are long tubes, just big enough for a patient to slide
into. IGMIT, however, resembles a huge pair of earmuffs. The magnet itself is
weak by MRI standards—only 0.2 tesla—and gives less detailed images
than a standard 1.5-tesla machine. “We trade off image quality for having it in
real time,” Bernstein says.

The muffs are about 28 centimetres apart, so there is only just enough room
for a surgeon to work in. So far, IGMIT has been used in only about a dozen
procedures, mostly tumour biopsies. Bernstein says more trials are needed to
decide if the advantages of real-time images outweigh the disadvantage of
operating “in a closet”.

It has taken six years and C$10 million (about ÂŁ4 million) to
reach this stage. Now the organisations working on the project—including
Toronto’s Sunnybrook Health Science Centre, the University of Toronto, ISG
Technologies, GE Medical Systems Canada and Northern Digital—are looking
into ways of making IGMIT cheaper and easier to use.

The fossilised bone was found near 20 stone tools, and has been dated at 2.3
million years old by researchers at the Institute of Human Origins in Berkeley,
California. Until now, the oldest specimens of Homo found near tools
were around 1.8 million years old, from Olduvai Gorge in Tanzania and Koobi Fora
in Kenya.

Most of the tools are fist-sized river cobbles that have been chipped to an
edge and presumably used for chopping. Stone flakes were also found, says
palaeoanthropologist William Kimbel of the institute. A small excavation in the
side of the hill revealed more tools and bones of unknown mammals.

Kimbel is not certain that the stone tools were made by members of the same
species as the individual whose jawbone was found. Two of the stone tools fit
together, suggesting that they were made at the site, rather than transported in
by flowing water. When Kimbel and his colleagues expand the
excavation—which initially covered only 2 square metres—they hope to
find evidence that the tools were used at the site, such as cut marks on
bone.

Alan Walker of Pennsylvania State University in University Park is intrigued.
“If the origin of genus Homo and the origin of stone tools were to
coincide, that would be really interesting,” he says.

Kimbel and his colleagues were searching the badlands of Ethiopia’s Hadar
region for remains that would fill the gap in the fossil record of human
evolution between two million and three million years ago. On the first day of
exploration, in 1994, two local members of the team found two pieces of jawbone.
“It was instantly apparent, when we put the two halves together, that we weren’t
dealing with a primitive Australopithecus jaw, but something much more
closely related to ourselves,” Kimbel says.

The jawbone includes the area beneath the nose, the nasal cavity, the
maxillary sinuses and many of the teeth on each side—enough anatomical
detail to identify it unequivocally as Homo, says Kimbel. The
researchers have not yet assigned a species: it may belong to Homo
habilis or Homo rudolfensis. “We’re not comfortable enough to say
it’s one or another at this time,” Kimbel says. A report of the discovery will
appear in the the December issue of the Journal of Human Evolution.

The location of the find, thought to be about 80 centimetres beneath a nearby
layer of volcanic ash, was fortunate, says geologist Bob Walter of the Institute
of Human Origins. He carried out the analysis with the help of Derek York, a
physicist at the University of Toronto. The ash could be dated to put a limit on
the age of the jawbone and tools.

York and Walter used argon-argon dating, which heats a single crystal of a
potassium-bearing mineral such as feldspar with increasingly powerful bursts
from a laser. Some 25 per cent of the grains analysed were between 5 million and
25 million years old, but the rest clustered around 2.33 million years ago.

RISING levels of carbon dioxide in the atmosphere may be causing more
than just global warming. They may also be responsible for an epidemic of
hayfever.

According to John Klironomos, a botanist at the University of Guelph, near
Toronto, doubling the level of CO₂ in the air can quadruple the number
of sneeze-provoking spores released by soil fungi. The level of CO₂ in
the air has risen from 280 parts per million in preindustrial times to about 355
parts per million today. It may double by about the middle of the next
century.

To study the effects of increased CO₂ on plants, Donald Zak, a
biologist at the University of Michigan, is growing 64 trembling aspens inside
chambers in a temperate hardwood forest. Half the trees are exposed to the
present level of CO₂ and the other half are exposed to twice as
much.

Last summer, Zak asked Klironomos to look at the effect of the CO₂
-rich atmosphere on the fungi that live in the soil beneath the aspens. These
fungi decompose the leaves and other detritus that fall from the trees.

Klironomos was surprised to find that the fungi in the CO₂-rich
atmosphere had gone into overdrive in churning out spores. “They were just
mass-producing spores,” he says. “When you looked at the [plant detritus] under
a microscope, you just saw a big film of spores.”

Not surprisingly, the air in the CO₂-rich chambers was thick with
spores—just like those that cause allergic reactions in millions of
people. Klironomos found between two and four times as many spores in the CO
₂-rich atmosphere as in the normal atmosphere. He believes that the fungi
put more effort into reproduction when their food is less nutritious. Plants
grown in an atmosphere rich in CO₂ contain proportionately less
nitrogen than normal, making them a poorer food for fungi, he says.

“More and more people around the world are suffering with respiratory
allergies, and future scenarios don’t look any better,” says Klironomos. “If I’m
right, they will only get worse.”