I don't see synchronized output when i comment the the line wait(1) in thread(). can I make them run at the same time (one after another) without having to use 'wait(1)'?

#include <boost/thread.hpp> 
#include <iostream> 

void wait(int seconds) 
{
  boost::this_thread::sleep(boost::posix_time::seconds(seconds)); 
}

boost::mutex mutex; 

void thread()
{
  for (int i = 0; i < 100; ++i) 
  {
    wait(1); 
    mutex.lock(); 
    std::cout << "Thread " << boost::this_thread::get_id() << ": " << i << std::endl; 
    mutex.unlock(); 
  }
}

int main()
{
  boost::thread t1(thread); 
  boost::thread t2(thread);

  t1.join();
  t2.join();
}