Active Record Timestamp

Active Record automatically timestamps create and update operations if the table has fields named created_at/created_on or updated_at/updated_on.

Timestamping can be turned off by setting:

config.active_record.record_timestamps = false

Timestamps are in the local timezone by default but you can use UTC by setting:

config.active_record.default_timezone = :utc

Time Zone aware attributes

By default, ActiveRecord::Base keeps all the datetime columns time zone aware by executing following code.

config.active_record.time_zone_aware_attributes = true

This feature can easily be turned off by assigning value false .

If your attributes are time zone aware and you desire to skip time zone conversion to the current Time.zone when reading certain attributes then you can do following:

class Topic < ActiveRecord::Base
  self.skip_time_zone_conversion_for_attributes = [:written_on]
end
Methods
I
Instance Public methods
initialize_dup(other)

Source: show | on GitHub 

# File activerecord/lib/active_record/timestamp.rb, line 40
def initialize_dup(other)
  clear_timestamp_attributes
end